linux-kernel - [PATCH 0/4] proc/kcore: performance optimizations

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Message-ID: <cover.1731115587.git.osandov@fb.com>
Date: Fri,  8 Nov 2024 17:28:38 -0800
From: Omar Sandoval <osandov@...ndov.com>
To: linux-fsdevel@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>
Cc: kernel-team@...com,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/4] proc/kcore: performance optimizations

From: Omar Sandoval <osandov@...com>

Hi,

The performance of /proc/kcore reads has been showing up as a bottleneck
for drgn. drgn scripts often spend ~25% of their time in the kernel
reading from /proc/kcore.

A lot of this overhead comes from silly inefficiencies. This patch
series fixes the low-hanging fruit. The fixes are all fairly small and
straightforward. The result is a 25% improvement in read latency in
micro-benchmarks (from ~235 nanoseconds to ~175) and a 15% improvement
in execution time for real-world drgn scripts.

Since I have a stake in /proc/kcore and have modified it several times,
the final patch volunteers me to maintain it.

Thanks,
Omar

Omar Sandoval (4):
  proc/kcore: mark proc entry as permanent
  proc/kcore: don't walk list on every read
  proc/kcore: use percpu_rw_semaphore for kclist_lock
  MAINTAINERS: add me as /proc/kcore maintainer

 MAINTAINERS     |  7 +++++
 fs/proc/kcore.c | 81 +++++++++++++++++++++++++------------------------
 2 files changed, 48 insertions(+), 40 deletions(-)

-- 
2.47.0