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Diffstat (limited to 'Documentation/filesystems/caching/fscache.rst')
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diff --git a/Documentation/filesystems/caching/fscache.rst b/Documentation/filesystems/caching/fscache.rst index 70de86922b6a..a74d7b052dc1 100644 --- a/Documentation/filesystems/caching/fscache.rst +++ b/Documentation/filesystems/caching/fscache.rst @@ -10,25 +10,25 @@ Overview This facility is a general purpose cache for network filesystems, though it could be used for caching other things such as ISO9660 filesystems too. -FS-Cache mediates between cache backends (such as CacheFS) and network +FS-Cache mediates between cache backends (such as CacheFiles) and network filesystems:: +---------+ - | | +--------------+ - | NFS |--+ | | - | | | +-->| CacheFS | - +---------+ | +----------+ | | /dev/hda5 | - | | | | +--------------+ - +---------+ +-->| | | - | | | |--+ - | AFS |----->| FS-Cache | - | | | |--+ - +---------+ +-->| | | - | | | | +--------------+ - +---------+ | +----------+ | | | - | | | +-->| CacheFiles | - | ISOFS |--+ | /var/cache | - | | +--------------+ + | | +--------------+ + | NFS |--+ | | + | | | +-->| CacheFS | + +---------+ | +----------+ | | /dev/hda5 | + | | | | +--------------+ + +---------+ +-------------->| | | + | | +-------+ | |--+ + | AFS |----->| | | FS-Cache | + | | | netfs |-->| |--+ + +---------+ +-->| lib | | | | + | | | | | | +--------------+ + +---------+ | +-------+ +----------+ | | | + | | | +-->| CacheFiles | + | 9P |--+ | /var/cache | + | | +--------------+ +---------+ Or to look at it another way, FS-Cache is a module that provides a caching @@ -84,101 +84,62 @@ then serving the pages out of that cache rather than the netfs inode because: one-off access of a small portion of it (such as might be done with the "file" program). -It instead serves the cache out in PAGE_SIZE chunks as and when requested by -the netfs('s) using it. +It instead serves the cache out in chunks as and when requested by the netfs +using it. FS-Cache provides the following facilities: - (1) More than one cache can be used at once. Caches can be selected + * More than one cache can be used at once. Caches can be selected explicitly by use of tags. - (2) Caches can be added / removed at any time. + * Caches can be added / removed at any time, even whilst being accessed. - (3) The netfs is provided with an interface that allows either party to + * The netfs is provided with an interface that allows either party to withdraw caching facilities from a file (required for (2)). - (4) The interface to the netfs returns as few errors as possible, preferring + * The interface to the netfs returns as few errors as possible, preferring rather to let the netfs remain oblivious. - (5) Cookies are used to represent indices, files and other objects to the - netfs. The simplest cookie is just a NULL pointer - indicating nothing - cached there. - - (6) The netfs is allowed to propose - dynamically - any index hierarchy it - desires, though it must be aware that the index search function is - recursive, stack space is limited, and indices can only be children of - indices. - - (7) Data I/O is done direct to and from the netfs's pages. The netfs - indicates that page A is at index B of the data-file represented by cookie - C, and that it should be read or written. The cache backend may or may - not start I/O on that page, but if it does, a netfs callback will be - invoked to indicate completion. The I/O may be either synchronous or - asynchronous. - - (8) Cookies can be "retired" upon release. At this point FS-Cache will mark - them as obsolete and the index hierarchy rooted at that point will get - recycled. - - (9) The netfs provides a "match" function for index searches. In addition to - saying whether a match was made or not, this can also specify that an - entry should be updated or deleted. - -(10) As much as possible is done asynchronously. - - -FS-Cache maintains a virtual indexing tree in which all indices, files, objects -and pages are kept. Bits of this tree may actually reside in one or more -caches:: - - FSDEF - | - +------------------------------------+ - | | - NFS AFS - | | - +--------------------------+ +-----------+ - | | | | - homedir mirror afs.org redhat.com - | | | - +------------+ +---------------+ +----------+ - | | | | | | - 00001 00002 00007 00125 vol00001 vol00002 - | | | | | - +---+---+ +-----+ +---+ +------+------+ +-----+----+ - | | | | | | | | | | | | | - PG0 PG1 PG2 PG0 XATTR PG0 PG1 DIRENT DIRENT DIRENT R/W R/O Bak - | | - PG0 +-------+ - | | - 00001 00003 - | - +---+---+ - | | | - PG0 PG1 PG2 - -In the example above, you can see two netfs's being backed: NFS and AFS. These -have different index hierarchies: - - * The NFS primary index contains per-server indices. Each server index is - indexed by NFS file handles to get data file objects. Each data file - objects can have an array of pages, but may also have further child - objects, such as extended attributes and directory entries. Extended - attribute objects themselves have page-array contents. - - * The AFS primary index contains per-cell indices. Each cell index contains - per-logical-volume indices. Each of volume index contains up to three - indices for the read-write, read-only and backup mirrors of those volumes. - Each of these contains vnode data file objects, each of which contains an - array of pages. - -The very top index is the FS-Cache master index in which individual netfs's -have entries. - -Any index object may reside in more than one cache, provided it only has index -children. Any index with non-index object children will be assumed to only -reside in one cache. + * There are three types of cookie: cache, volume and data file cookies. + Cache cookies represent the cache as a whole and are not normally visible + to the netfs; the netfs gets a volume cookie to represent a collection of + files (typically something that a netfs would get for a superblock); and + data file cookies are used to cache data (something that would be got for + an inode). + + * Volumes are matched using a key. This is a printable string that is used + to encode all the information that might be needed to distinguish one + superblock, say, from another. This would be a compound of things like + cell name or server address, volume name or share path. It must be a + valid pathname. + + * Cookies are matched using a key. This is a binary blob and is used to + represent the object within a volume (so the volume key need not form + part of the blob). This might include things like an inode number and + uniquifier or a file handle. + + * Cookie resources are set up and pinned by marking the cookie in-use. + This prevents the backing resources from being culled. Timed garbage + collection is employed to eliminate cookies that haven't been used for a + short while, thereby reducing resource overload. This is intended to be + used when a file is opened or closed. + + A cookie can be marked in-use multiple times simultaneously; each mark + must be unused. + + * Begin/end access functions are provided to delay cache withdrawal for the + duration of an operation and prevent structs from being freed whilst + we're looking at them. + + * Data I/O is done by asynchronous DIO to/from a buffer described by the + netfs using an iov_iter. + + * An invalidation facility is available to discard data from the cache and + to deal with I/O that's in progress that is accessing old data. + + * Cookies can be "retired" upon release, thereby causing the object to be + removed from the cache. The netfs API to FS-Cache can be found in: @@ -189,11 +150,6 @@ The cache backend API to FS-Cache can be found in: Documentation/filesystems/caching/backend-api.rst -A description of the internal representations and object state machine can be -found in: - - Documentation/filesystems/caching/object.rst - Statistical Information ======================= @@ -201,333 +157,162 @@ Statistical Information If FS-Cache is compiled with the following options enabled:: CONFIG_FSCACHE_STATS=y - CONFIG_FSCACHE_HISTOGRAM=y -then it will gather certain statistics and display them through a number of -proc files. +then it will gather certain statistics and display them through: -/proc/fs/fscache/stats ----------------------- + /proc/fs/fscache/stats - This shows counts of a number of events that can happen in FS-Cache: +This shows counts of a number of events that can happen in FS-Cache: +--------------+-------+-------------------------------------------------------+ |CLASS |EVENT |MEANING | +==============+=======+=======================================================+ -|Cookies |idx=N |Number of index cookies allocated | -+ +-------+-------------------------------------------------------+ -| |dat=N |Number of data storage cookies allocated | +|Cookies |n=N |Number of data storage cookies allocated | + +-------+-------------------------------------------------------+ -| |spc=N |Number of special cookies allocated | -+--------------+-------+-------------------------------------------------------+ -|Objects |alc=N |Number of objects allocated | -+ +-------+-------------------------------------------------------+ -| |nal=N |Number of object allocation failures | +| |v=N |Number of volume index cookies allocated | + +-------+-------------------------------------------------------+ -| |avl=N |Number of objects that reached the available state | -+ +-------+-------------------------------------------------------+ -| |ded=N |Number of objects that reached the dead state | -+--------------+-------+-------------------------------------------------------+ -|ChkAux |non=N |Number of objects that didn't have a coherency check | +| |vcol=N |Number of volume index key collisions | + +-------+-------------------------------------------------------+ -| |ok=N |Number of objects that passed a coherency check | -+ +-------+-------------------------------------------------------+ -| |upd=N |Number of objects that needed a coherency data update | -+ +-------+-------------------------------------------------------+ -| |obs=N |Number of objects that were declared obsolete | -+--------------+-------+-------------------------------------------------------+ -|Pages |mrk=N |Number of pages marked as being cached | -| |unc=N |Number of uncache page requests seen | +| |voom=N |Number of OOM events when allocating volume cookies | +--------------+-------+-------------------------------------------------------+ |Acquire |n=N |Number of acquire cookie requests seen | + +-------+-------------------------------------------------------+ -| |nul=N |Number of acq reqs given a NULL parent | -+ +-------+-------------------------------------------------------+ -| |noc=N |Number of acq reqs rejected due to no cache available | -+ +-------+-------------------------------------------------------+ | |ok=N |Number of acq reqs succeeded | + +-------+-------------------------------------------------------+ -| |nbf=N |Number of acq reqs rejected due to error | -+ +-------+-------------------------------------------------------+ | |oom=N |Number of acq reqs failed on ENOMEM | +--------------+-------+-------------------------------------------------------+ -|Lookups |n=N |Number of lookup calls made on cache backends | +|LRU |n=N |Number of cookies currently on the LRU | + +-------+-------------------------------------------------------+ -| |neg=N |Number of negative lookups made | +| |exp=N |Number of cookies expired off of the LRU | + +-------+-------------------------------------------------------+ -| |pos=N |Number of positive lookups made | +| |rmv=N |Number of cookies removed from the LRU | + +-------+-------------------------------------------------------+ -| |crt=N |Number of objects created by lookup | +| |drp=N |Number of LRU'd cookies relinquished/withdrawn | + +-------+-------------------------------------------------------+ -| |tmo=N |Number of lookups timed out and requeued | +| |at=N |Time till next LRU cull (jiffies) | ++--------------+-------+-------------------------------------------------------+ +|Invals |n=N |Number of invalidations | +--------------+-------+-------------------------------------------------------+ |Updates |n=N |Number of update cookie requests seen | + +-------+-------------------------------------------------------+ -| |nul=N |Number of upd reqs given a NULL parent | +| |rsz=N |Number of resize requests | + +-------+-------------------------------------------------------+ -| |run=N |Number of upd reqs granted CPU time | +| |rsn=N |Number of skipped resize requests | +--------------+-------+-------------------------------------------------------+ |Relinqs |n=N |Number of relinquish cookie requests seen | + +-------+-------------------------------------------------------+ -| |nul=N |Number of rlq reqs given a NULL parent | +| |rtr=N |Number of rlq reqs with retire=true | + +-------+-------------------------------------------------------+ -| |wcr=N |Number of rlq reqs waited on completion of creation | +| |drop=N |Number of cookies no longer blocking re-acquisition | +--------------+-------+-------------------------------------------------------+ -|AttrChg |n=N |Number of attribute changed requests seen | -+ +-------+-------------------------------------------------------+ -| |ok=N |Number of attr changed requests queued | -+ +-------+-------------------------------------------------------+ -| |nbf=N |Number of attr changed rejected -ENOBUFS | +|NoSpace |nwr=N |Number of write requests refused due to lack of space | + +-------+-------------------------------------------------------+ -| |oom=N |Number of attr changed failed -ENOMEM | +| |ncr=N |Number of create requests refused due to lack of space | + +-------+-------------------------------------------------------+ -| |run=N |Number of attr changed ops given CPU time | +| |cull=N |Number of objects culled to make space | +--------------+-------+-------------------------------------------------------+ -|Allocs |n=N |Number of allocation requests seen | +|IO |rd=N |Number of read operations in the cache | + +-------+-------------------------------------------------------+ -| |ok=N |Number of successful alloc reqs | -+ +-------+-------------------------------------------------------+ -| |wt=N |Number of alloc reqs that waited on lookup completion | -+ +-------+-------------------------------------------------------+ -| |nbf=N |Number of alloc reqs rejected -ENOBUFS | -+ +-------+-------------------------------------------------------+ -| |int=N |Number of alloc reqs aborted -ERESTARTSYS | -+ +-------+-------------------------------------------------------+ -| |ops=N |Number of alloc reqs submitted | -+ +-------+-------------------------------------------------------+ -| |owt=N |Number of alloc reqs waited for CPU time | -+ +-------+-------------------------------------------------------+ -| |abt=N |Number of alloc reqs aborted due to object death | -+--------------+-------+-------------------------------------------------------+ -|Retrvls |n=N |Number of retrieval (read) requests seen | -+ +-------+-------------------------------------------------------+ -| |ok=N |Number of successful retr reqs | -+ +-------+-------------------------------------------------------+ -| |wt=N |Number of retr reqs that waited on lookup completion | -+ +-------+-------------------------------------------------------+ -| |nod=N |Number of retr reqs returned -ENODATA | -+ +-------+-------------------------------------------------------+ -| |nbf=N |Number of retr reqs rejected -ENOBUFS | -+ +-------+-------------------------------------------------------+ -| |int=N |Number of retr reqs aborted -ERESTARTSYS | -+ +-------+-------------------------------------------------------+ -| |oom=N |Number of retr reqs failed -ENOMEM | -+ +-------+-------------------------------------------------------+ -| |ops=N |Number of retr reqs submitted | -+ +-------+-------------------------------------------------------+ -| |owt=N |Number of retr reqs waited for CPU time | -+ +-------+-------------------------------------------------------+ -| |abt=N |Number of retr reqs aborted due to object death | -+--------------+-------+-------------------------------------------------------+ -|Stores |n=N |Number of storage (write) requests seen | -+ +-------+-------------------------------------------------------+ -| |ok=N |Number of successful store reqs | -+ +-------+-------------------------------------------------------+ -| |agn=N |Number of store reqs on a page already pending storage | -+ +-------+-------------------------------------------------------+ -| |nbf=N |Number of store reqs rejected -ENOBUFS | -+ +-------+-------------------------------------------------------+ -| |oom=N |Number of store reqs failed -ENOMEM | -+ +-------+-------------------------------------------------------+ -| |ops=N |Number of store reqs submitted | -+ +-------+-------------------------------------------------------+ -| |run=N |Number of store reqs granted CPU time | -+ +-------+-------------------------------------------------------+ -| |pgs=N |Number of pages given store req processing time | -+ +-------+-------------------------------------------------------+ -| |rxd=N |Number of store reqs deleted from tracking tree | -+ +-------+-------------------------------------------------------+ -| |olm=N |Number of store reqs over store limit | -+--------------+-------+-------------------------------------------------------+ -|VmScan |nos=N |Number of release reqs against pages with no | -| | |pending store | -+ +-------+-------------------------------------------------------+ -| |gon=N |Number of release reqs against pages stored by | -| | |time lock granted | -+ +-------+-------------------------------------------------------+ -| |bsy=N |Number of release reqs ignored due to in-progress store| -+ +-------+-------------------------------------------------------+ -| |can=N |Number of page stores cancelled due to release req | -+--------------+-------+-------------------------------------------------------+ -|Ops |pend=N |Number of times async ops added to pending queues | -+ +-------+-------------------------------------------------------+ -| |run=N |Number of times async ops given CPU time | -+ +-------+-------------------------------------------------------+ -| |enq=N |Number of times async ops queued for processing | -+ +-------+-------------------------------------------------------+ -| |can=N |Number of async ops cancelled | -+ +-------+-------------------------------------------------------+ -| |rej=N |Number of async ops rejected due to object | -| | |lookup/create failure | -+ +-------+-------------------------------------------------------+ -| |ini=N |Number of async ops initialised | -+ +-------+-------------------------------------------------------+ -| |dfr=N |Number of async ops queued for deferred release | -+ +-------+-------------------------------------------------------+ -| |rel=N |Number of async ops released | -| | |(should equal ini=N when idle) | -+ +-------+-------------------------------------------------------+ -| |gc=N |Number of deferred-release async ops garbage collected | -+--------------+-------+-------------------------------------------------------+ -|CacheOp |alo=N |Number of in-progress alloc_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |luo=N |Number of in-progress lookup_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |luc=N |Number of in-progress lookup_complete() cache ops | -+ +-------+-------------------------------------------------------+ -| |gro=N |Number of in-progress grab_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |upo=N |Number of in-progress update_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |dro=N |Number of in-progress drop_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |pto=N |Number of in-progress put_object() cache ops | -+ +-------+-------------------------------------------------------+ -| |syn=N |Number of in-progress sync_cache() cache ops | -+ +-------+-------------------------------------------------------+ -| |atc=N |Number of in-progress attr_changed() cache ops | -+ +-------+-------------------------------------------------------+ -| |rap=N |Number of in-progress read_or_alloc_page() cache ops | -+ +-------+-------------------------------------------------------+ -| |ras=N |Number of in-progress read_or_alloc_pages() cache ops | -+ +-------+-------------------------------------------------------+ -| |alp=N |Number of in-progress allocate_page() cache ops | -+ +-------+-------------------------------------------------------+ -| |als=N |Number of in-progress allocate_pages() cache ops | -+ +-------+-------------------------------------------------------+ -| |wrp=N |Number of in-progress write_page() cache ops | -+ +-------+-------------------------------------------------------+ -| |ucp=N |Number of in-progress uncache_page() cache ops | -+ +-------+-------------------------------------------------------+ -| |dsp=N |Number of in-progress dissociate_pages() cache ops | -+--------------+-------+-------------------------------------------------------+ -|CacheEv |nsp=N |Number of object lookups/creations rejected due to | -| | |lack of space | -+ +-------+-------------------------------------------------------+ -| |stl=N |Number of stale objects deleted | -+ +-------+-------------------------------------------------------+ -| |rtr=N |Number of objects retired when relinquished | -+ +-------+-------------------------------------------------------+ -| |cul=N |Number of objects culled | +| |wr=N |Number of write operations in the cache | +--------------+-------+-------------------------------------------------------+ +Netfslib will also add some stats counters of its own. -/proc/fs/fscache/histogram --------------------------- +Cache List +========== - :: +FS-Cache provides a list of cache cookies: - cat /proc/fs/fscache/histogram - JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS - ===== ===== ========= ========= ========= ========= ========= + /proc/fs/fscache/cookies - This shows the breakdown of the number of times each amount of time - between 0 jiffies and HZ-1 jiffies a variety of tasks took to run. The - columns are as follows: +This will look something like:: - ========= ======================================================= - COLUMN TIME MEASUREMENT - ========= ======================================================= - OBJ INST Length of time to instantiate an object - OP RUNS Length of time a call to process an operation took - OBJ RUNS Length of time a call to process an object event took - RETRV DLY Time between an requesting a read and lookup completing - RETRIEVLS Time between beginning and end of a retrieval - ========= ======================================================= + # cat /proc/fs/fscache/caches + CACHE REF VOLS OBJS ACCES S NAME + ======== ===== ===== ===== ===== = =============== + 00000001 2 1 2123 1 A default - Each row shows the number of events that took a particular range of times. - Each step is 1 jiffy in size. The JIFS column indicates the particular - jiffy range covered, and the SECS field the equivalent number of seconds. +where the columns are: + ======= =============================================================== + COLUMN DESCRIPTION + ======= =============================================================== + CACHE Cache cookie debug ID (also appears in traces) + REF Number of references on the cache cookie + VOLS Number of volumes cookies in this cache + OBJS Number of cache objects in use + ACCES Number of accesses pinning the cache + S State + NAME Name of the cache. + ======= =============================================================== + +The state can be (-) Inactive, (P)reparing, (A)ctive, (E)rror or (W)ithdrawing. -Object List +Volume List =========== -If CONFIG_FSCACHE_OBJECT_LIST is enabled, the FS-Cache facility will maintain a -list of all the objects currently allocated and allow them to be viewed -through:: +FS-Cache provides a list of volume cookies: - /proc/fs/fscache/objects + /proc/fs/fscache/volumes This will look something like:: - [root@andromeda ~]# head /proc/fs/fscache/objects - OBJECT PARENT STAT CHLDN OPS OOP IPR EX READS EM EV F S | NETFS_COOKIE_DEF TY FL NETFS_DATA OBJECT_KEY, AUX_DATA - ======== ======== ==== ===== === === === == ===== == == = = | ================ == == ================ ================ - 17e4b 2 ACTV 0 0 0 0 0 0 7b 4 0 0 | NFS.fh DT 0 ffff88001dd82820 010006017edcf8bbc93b43298fdfbe71e50b57b13a172c0117f38472, e567634700000000000000000000000063f2404a000000000000000000000000c9030000000000000000000063f2404a - 1693a 2 ACTV 0 0 0 0 0 0 7b 4 0 0 | NFS.fh DT 0 ffff88002db23380 010006017edcf8bbc93b43298fdfbe71e50b57b1e0162c01a2df0ea6, 420ebc4a000000000000000000000000420ebc4a0000000000000000000000000e1801000000000000000000420ebc4a + VOLUME REF nCOOK ACC FL CACHE KEY + ======== ===== ===== === == =============== ================ + 00000001 55 54 1 00 default afs,example.com,100058 -where the first set of columns before the '|' describe the object: +where the columns are: ======= =============================================================== COLUMN DESCRIPTION ======= =============================================================== - OBJECT Object debugging ID (appears as OBJ%x in some debug messages) - PARENT Debugging ID of parent object - STAT Object state - CHLDN Number of child objects of this object - OPS Number of outstanding operations on this object - OOP Number of outstanding child object management operations - IPR - EX Number of outstanding exclusive operations - READS Number of outstanding read operations - EM Object's event mask - EV Events raised on this object - F Object flags - S Object work item busy state mask (1:pending 2:running) + VOLUME The volume cookie debug ID (also appears in traces) + REF Number of references on the volume cookie + nCOOK Number of cookies in the volume + ACC Number of accesses pinning the cache + FL Flags on the volume cookie + CACHE Name of the cache or "-" + KEY The indexing key for the volume ======= =============================================================== -and the second set of columns describe the object's cookie, if present: - - ================ ====================================================== - COLUMN DESCRIPTION - ================ ====================================================== - NETFS_COOKIE_DEF Name of netfs cookie definition - TY Cookie type (IX - index, DT - data, hex - special) - FL Cookie flags - NETFS_DATA Netfs private data stored in the cookie - OBJECT_KEY Object key } 1 column, with separating comma - AUX_DATA Object aux data } presence may be configured - ================ ====================================================== - -The data shown may be filtered by attaching the a key to an appropriate keyring -before viewing the file. Something like:: - - keyctl add user fscache:objlist <restrictions> @s - -where <restrictions> are a selection of the following letters: - == ========================================================= - K Show hexdump of object key (don't show if not given) - A Show hexdump of object aux data (don't show if not given) - == ========================================================= +Cookie List +=========== -and the following paired letters: +FS-Cache provides a list of cookies: - == ========================================================= - C Show objects that have a cookie - c Show objects that don't have a cookie - B Show objects that are busy - b Show objects that aren't busy - W Show objects that have pending writes - w Show objects that don't have pending writes - R Show objects that have outstanding reads - r Show objects that don't have outstanding reads - S Show objects that have work queued - s Show objects that don't have work queued - == ========================================================= + /proc/fs/fscache/cookies -If neither side of a letter pair is given, then both are implied. For example: +This will look something like:: - keyctl add user fscache:objlist KB @s + # head /proc/fs/fscache/cookies + COOKIE VOLUME REF ACT ACC S FL DEF + ======== ======== === === === = == ================ + 00000435 00000001 1 0 -1 - 08 0000000201d080070000000000000000, 0000000000000000 + 00000436 00000001 1 0 -1 - 00 0000005601d080080000000000000000, 0000000000000051 + 00000437 00000001 1 0 -1 - 08 00023b3001d0823f0000000000000000, 0000000000000000 + 00000438 00000001 1 0 -1 - 08 0000005801d0807b0000000000000000, 0000000000000000 + 00000439 00000001 1 0 -1 - 08 00023b3201d080a10000000000000000, 0000000000000000 + 0000043a 00000001 1 0 -1 - 08 00023b3401d080a30000000000000000, 0000000000000000 + 0000043b 00000001 1 0 -1 - 08 00023b3601d080b30000000000000000, 0000000000000000 + 0000043c 00000001 1 0 -1 - 08 00023b3801d080b40000000000000000, 0000000000000000 -shows objects that are busy, and lists their object keys, but does not dump -their auxiliary data. It also implies "CcWwRrSs", but as 'B' is given, 'b' is -not implied. +where the columns are: -By default all objects and all fields will be shown. + ======= =============================================================== + COLUMN DESCRIPTION + ======= =============================================================== + COOKIE The cookie debug ID (also appears in traces) + VOLUME The parent volume cookie debug ID + REF Number of references on the volume cookie + ACT Number of times the cookie is marked for in use + ACC Number of access pins in the cookie + S State of the cookie + FL Flags on the cookie + DEF Key, auxiliary data + ======= =============================================================== Debugging @@ -549,10 +334,8 @@ This is a bitmask of debugging streams to enable: 3 8 Cookie management Function entry trace 4 16 Function exit trace 5 32 General - 6 64 Page handling Function entry trace - 7 128 Function exit trace - 8 256 General - 9 512 Operation management Function entry trace + 6-8 (Not used) + 9 512 I/O operation management Function entry trace 10 1024 Function exit trace 11 2048 General ======= ======= =============================== ======================= @@ -560,6 +343,6 @@ This is a bitmask of debugging streams to enable: The appropriate set of values should be OR'd together and the result written to the control file. For example:: - echo $((1|8|64)) >/sys/module/fscache/parameters/debug + echo $((1|8|512)) >/sys/module/fscache/parameters/debug will turn on all function entry debugging. |