When commit 390390240145 ("nfsd: don't allow nfsd threads to be
signalled.") is backported to 5.10, it was adjusted considering commit
3feac2b55293 ("sunrpc: exclude from freezer when waiting for requests:").
However, 3feac2b55293 is based on commit f6e70aab9dfe ("SUNRPC: refresh
rq_pages using a bulk page allocator"), which converted page-by-page
allocation to a batch allocation, so schedule_timeout() is placed
un-nested.
As a result, the backported commit 7229200f6866 ("nfsd: don't allow nfsd
threads to be signalled.") placed freezable_schedule_timeout() in the wrong
place.
Now, freezable_schedule_timeout() is called after every successful page
allocation, and we see 30%+ performance regression on 5.10.220 in our
test suite.
Let's move it to the correct place so that freezable_schedule_timeout()
is called only when page allocation fails.
Fixes: 7229200f6866 ("nfsd: don't allow nfsd threads to be signalled.")
Reported-by: Hughdan Liu <hughliu@amazon.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 3903902401451b1cd9d797a8c79769eb26ac7fe5 ]
The original implementation of nfsd used signals to stop threads during
shutdown.
In Linux 2.3.46pre5 nfsd gained the ability to shutdown threads
internally it if was asked to run "0" threads. After this user-space
transitioned to using "rpc.nfsd 0" to stop nfsd and sending signals to
threads was no longer an important part of the API.
In commit 3ebdbe5203a8 ("SUNRPC: discard svo_setup and rename
svc_set_num_threads_sync()") (v5.17-rc1~75^2~41) we finally removed the
use of signals for stopping threads, using kthread_stop() instead.
This patch makes the "obvious" next step and removes the ability to
signal nfsd threads - or any svc threads. nfsd stops allowing signals
and we don't check for their delivery any more.
This will allow for some simplification in later patches.
A change worth noting is in nfsd4_ssc_setup_dul(). There was previously
a signal_pending() check which would only succeed when the thread was
being shut down. It should really have tested kthread_should_stop() as
well. Now it just does the latter, not the former.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
[ cel: adjusted to apply to v5.10.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7827c81f0248e3c2f40d438b020f3d222f002171 ]
The premise that "Once an svc thread is scheduled and executing an
RPC, no other processes will touch svc_rqst::rq_flags" is false.
svc_xprt_enqueue() examines the RQ_BUSY flag in scheduled nfsd
threads when determining which thread to wake up next.
Found via KCSAN.
Fixes: 28df0988815f ("SUNRPC: Use RMW bitops in single-threaded hot paths")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 28df0988815f63e2af5e6718193c9f68681ad7ff ]
I noticed CPU pipeline stalls while using perf.
Once an svc thread is scheduled and executing an RPC, no other
processes will touch svc_rqst::rq_flags. Thus bus-locked atomics are
not needed outside the svc thread scheduler.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c7d7ec8f043e53ad16e30f5ebb8b9df415ec0f2b ]
Clean up: svc_shutdown_net() now does nothing but call
svc_close_net(). Replace all external call sites.
svc_close_net() is renamed to be the inverse of svc_xprt_create().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 4355d767a21b9445958fc11bce9a9701f76529d3 ]
Clean up: Use the "svc_xprt_<task>" function naming convention as
is used for other external APIs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 352ad31448fecc78a2e9b78da64eea5d63b8d0ce ]
Clean up: Use the "svc_xprt_<task>" function naming convention as
is used for other external APIs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c0219c499799c1e92bd570c15a47e6257a27bb15 ]
Neil says:
"These functions were separated in commit 0971374e2818 ("SUNRPC:
Reduce contention in svc_xprt_enqueue()") so that the XPT_BUSY check
happened before taking any spinlocks.
We have since moved or removed the spinlocks so the extra test is
fairly pointless."
I've made this a separate patch in case the XPT_BUSY change has
unexpected consequences and needs to be reverted.
Suggested-by: Neil Brown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a9ff2e99e9fa501ec965da03c18a5422b37a2f44 ]
We have never been able to track down and address the underlying
cause of the performance issues with workqueue-based service
support. svo_enqueue_xprt is called multiple times per RPC, so
it adds instruction path length, but always ends up at the same
function: svc_xprt_do_enqueue(). We do not anticipate needing
this flexibility for dynamic nfsd thread management support.
As a micro-optimization, remove .svo_enqueue_xprt because
Spectre/Meltdown makes virtual function calls more costly.
This change essentially reverts commit b9e13cdfac70 ("nfsd/sunrpc:
turn enqueueing a svc_xprt into a svc_serv operation").
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2f0f88f42f2eab0421ed37d7494de9124fdf0d34 ]
Replacing a page in rq_pages[] requires a get_page(), which is a
bus-locked operation, and a put_page(), which can be even more
costly.
To reduce the cost of replacing a page in rq_pages[], batch the
put_page() operations by collecting "freed" pages in a pagevec,
and then release those pages when the pagevec is full. This
pagevec is also emptied when each RPC completes.
[ cel: adjusted to apply without f6e70aab9dfe ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7dcfbd86adc45f6d6b37278efd22530cf80ab474 ]
Prepare svc_xprt_received() to be called from transport code instead
of from generic RPC server code.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
