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[86.156.84.164]) by smtp.gmail.com with ESMTPSA id s1-20020adff801000000b00300aee6c9cesm21700273wrp.20.2023.04.28.10.40.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Apr 2023 10:40:19 -0700 (PDT) Date: Fri, 28 Apr 2023 18:40:18 +0100 From: Lorenzo Stoakes To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, torvalds@linux-foundation.org, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 1/1] mm: change per-VMA lock statistics to be disabled by default Message-ID: <443a229c-4923-4c87-ba38-6ab4979d8f2a@lucifer.local> References: <20230428173533.18158-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230428173533.18158-1-surenb@google.com> X-Rspamd-Queue-Id: 3957118001C X-Stat-Signature: 9xxwfqyimc95jj3sris6bitwx1cry66x X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1682703621-602717 X-HE-Meta: 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 MOFVyJj+ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 28, 2023 at 10:35:33AM -0700, Suren Baghdasaryan wrote: > Change CONFIG_PER_VMA_LOCK_STATS to be disabled by default, as most > users don't need it. Add configuration help to clarify its usage. > > Fixes: 52f238653e45 ("mm: introduce per-VMA lock statistics") > Suggested-by: Linus Torvalds > Signed-off-by: Suren Baghdasaryan > --- > mm/Kconfig.debug | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 6dae63b46368..a925415b4d10 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -274,6 +274,12 @@ config DEBUG_KMEMLEAK_AUTO_SCAN > config PER_VMA_LOCK_STATS > bool "Statistics for per-vma locks" > depends on PER_VMA_LOCK > - default y > help > - Statistics for per-vma locks. > + Say Y here to enable success, retry and failure counters of page > + faults handled under protection of per-vma locks. When enabled, the > + counters are exposed in /proc/vmstat. This information is useful for > + kernel developers to evaluate effectiveness of per-vma locks and to > + identify pathological cases. Counting these events introduces a small > + overhead in the page fault path. > + > + If in doubt, say N. > -- > 2.40.1.495.gc816e09b53d-goog > Reviewed-by: Lorenzo Stoakes