srcu: Block less aggressively for expedited grace periods

Commit 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers
from consuming CPU") fixed a problem where a long-running expedited SRCU
grace period could block kernel live patching.  It did so by giving up
on expediting once a given SRCU expedited grace period grew too old.

Unfortunately, this added excessive delays to boots of virtual embedded
systems specifying "-bios QEMU_EFI.fd" to qemu.  This commit therefore
makes the transition away from expediting less aggressive, increasing
the per-grace-period phase number of non-sleeping polls of readers from
one to three and increasing the required grace-period age from one jiffy
(actually from zero to one jiffies) to two jiffies (actually from one
to two jiffies).

Fixes: 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers from consuming CPU")
Signed-off-by: Paul E. McKenney <[email protected]>
Reported-by: Zhangfei Gao <[email protected]>
Reported-by: chenxiang (M)" <[email protected]>
Cc: Shameerali Kolothum Thodi  <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Reviewed-by: Neeraj Upadhyay <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/

0 files changed, 0 insertions, 0 deletions