diff options
| author | Omar Sandoval <[email protected]> | 2018-08-21 21:55:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2018-08-22 10:52:46 -0700 |
| commit | bf991c2231117d50a7645792b514354fc8d19dae (patch) | |
| tree | c7c74e6d467774e97be1a0022b26c1047a7465b8 | |
| parent | 37e949bd5293ddb70acf236eedf2ae8caa1db57b (diff) | |
proc/kcore: optimize multiple page reads
The current code does a full search of the segment list every time for
every page. This is wasteful, since it's almost certain that the next
page will be in the same segment. Instead, check if the previous segment
covers the current page before doing the list search.
Link: http://lkml.kernel.org/r/fd346c11090cf93d867e01b8d73a6567c5ac6361.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Bhupesh Sharma <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: James Morse <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | fs/proc/kcore.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 808ef9afd084..758c14e46a44 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -428,10 +428,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; + m = NULL; while (buflen) { - list_for_each_entry(m, &kclist_head, list) { - if (start >= m->addr && start < (m->addr+m->size)) - break; + /* + * If this is the first iteration or the address is not within + * the previous entry, search for a matching entry. + */ + if (!m || start < m->addr || start >= m->addr + m->size) { + list_for_each_entry(m, &kclist_head, list) { + if (start >= m->addr && + start < m->addr + m->size) + break; + } } if (&m->list == &kclist_head) { |