From: Tim Menninger <tmenninger@everpuredata.com>
To: Harry Yoo <harry@kernel.org>
Cc: linux-mm@kvack.org, Chuck Lever <cel@kernel.org>,
linux-nfs@vger.kernel.org, Jon Curley <jcurley@everpuredata.com>,
Eric Badger <ebadger@everpuredata.com>,
Vlastimil Babka <vbabka@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
James Clark <james.clark@linaro.org>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [SLUB] nfs_page cmpxchg_double_fail and perf lock perturbation on dual-socket NFS/RDMA
Date: Thu, 17 Sep 2026 16:25:33 +0000 [thread overview]
Message-ID: <20260917162533.600472-1-tmenninger@everpuredata.com> (raw)
In-Reply-To: <aqvy8NqRRRmUlxjR@thinkstation>
It reproduces with slab_nomerge.
I booted the same kernel with:
$ cat /proc/cmdline
... slab_nomerge ...
Uninstrumented throughput remains in the high-45 to low-46 GB/s
range, as before. During perf lock it was around 30 GB/s in these
runs, versus roughly 25 GB/s previously.
The dominant lock measurements are essentially unchanged:
default slab_nomerge
unpinned/node0
contentions 4,782,839 4,858,759
total wait 14.39 min 14.26 min
average wait 180.47 us 176.13 us
node0/node0
contentions 4,582,012 4,686,729
total wait 14.13 min 14.34 min
average wait 185.05 us 183.53 us
unpinned/balanced
contentions 4,572,196 4,544,677
total wait 12.81 min 12.56 min
average wait 168.14 us 165.84 us
The uninstrumented cmpxchg_double_fail deltas were:
default slab_nomerge
unpinned/node0 7,471 8,892
node0/node0 713 457
unpinned/balanced 1,503 1,504
The CPU-utilization change while perf lock is active also remains.
System-wide %idle for uninstrumented/instrumented windows was:
default slab_nomerge
uninstr. instr. uninstr. instr.
unpinned/node0 31.46% 3.60% 23.02% 2.15%
node0/node0 84.26% 12.07% 84.62% 11.85%
unpinned/balanced 66.86% 14.83% 66.58% 14.78%
Thanks,
Tim
next prev parent reply other threads:[~2026-09-17 16:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260916232227.4098143-1-tmenninger@everpuredata.com>
[not found] ` <aqvq8-6IJBDer90O@thinkstation>
2026-09-17 14:10 ` Harry Yoo
2026-09-17 15:29 ` Peter Zijlstra
2026-09-18 7:04 ` Namhyung Kim
2026-09-17 16:25 ` Tim Menninger [this message]
2026-09-18 7:08 ` Vlastimil Babka (SUSE)
2026-09-21 15:31 ` Harry Yoo
2026-09-21 23:27 ` Tim Menninger
2026-09-18 7:14 ` Namhyung Kim
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