svcrdma: Fewer calls to wake_up() in Send completion handler

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Because wake_up() takes an IRQ-safe lock, it can be expensive,
especially to call inside of a single-threaded completion handler.
What's more, the Send wait queue almost never has waiters, so
most of the time, this is an expensive no-op.

As always, the goal is to reduce the average overhead of each
completion, because a transport's completion handlers are single-
threaded on one CPU core. This change reduces CPU utilization of
the Send completion thread by 2-3% on my server.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-By: Tom Talpey <tom@talpey.com>

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This commit is contained in:

Chuck Lever 2021-07-07 14:57:28 -04:00

parent cd2d644ddb

commit 6c8c84f525

3 changed files with 18 additions and 8 deletions

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1

include/linux/sunrpc/svc_rdma.h

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7

net/sunrpc/xprtrdma/svc_rdma_rw.c

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18

net/sunrpc/xprtrdma/svc_rdma_sendto.c

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