From: Thomas Gleixner <tglx@linutronix.de>
To: Axel Rasmussen <axelrasmussen@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Davidlohr Bueso <dbueso@suse.de>, Ingo Molnar <mingo@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Jerome Glisse <jglisse@redhat.com>,
Laurent Dufour <ldufour@linux.ibm.com>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Matthew Wilcox <willy@infradead.org>,
Michel Lespinasse <walken@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Will Deacon <will@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org,
"AKASHI Takahiro" <takahiro.akashi@linaro.org>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Alexander Potapenko" <glider@google.com>,
"Alexey Dobriyan" <adobriyan@gmail.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andrei Vagin" <avagin@gmail.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Brendan Higgins" <brendanhiggins@google.com>,
chenqiwu <chenqiwu@xiaomi.com>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Christian Kellner" <christian@kellner.me>,
"Corentin Labbe" <clabbe@baylibre.com>,
"Daniel Jordan" <daniel.m.jordan@oracle.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"David Gow" <davidgow@google.com>,
"David S. Miller" <davem@davemloft.net>,
"Dmitry V. Levin" <ldv@altlinux.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Eugene Syromiatnikov" <esyr@redhat.com>,
"Jamie Liu" <jamieliu@google.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"John Garry" <john.garry@huawei.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Jonathan Adams" <jwadams@google.com>,
"Junaid Shahid" <junaids@google.com>,
"Kees Cook" <keescook@chromium.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Konstantin Khlebnikov" <khlebnikov@yandex-team.ru>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Masahiro Yamada" <yamada.masahiro@socionext.com>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Michal Hocko" <mhocko@suse.com>,
"Mikhail Zaslonko" <zaslonko@linux.ibm.com>,
"Petr Mladek" <pmladek@suse.com>,
"Ralph Campbell" <rcampbell@nvidia.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Roman Gushchin" <guro@fb.com>,
"Shakeel Butt" <shakeelb@google.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Tal Gilboa" <talgi@mellanox.com>,
"Uwe Kleine-König" <uwe@kleine-koenig.org>,
"Vincenzo Frascino" <vincenzo.frascino@arm.com>,
"Yang Shi" <yang.shi@linux.alibaba.com>,
"Yu Zhao" <yuzhao@google.com>,
"Axel Rasmussen" <axelrasmussen@google.com>
Subject: Re: [PATCH v2 0/7] Add histogram measuring mmap_lock contention latency
Date: Fri, 29 May 2020 07:32:17 +0200 [thread overview]
Message-ID: <87wo4vmhlq.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200528235238.74233-1-axelrasmussen@google.com>
Axel,
Axel Rasmussen <axelrasmussen@google.com> writes:
> The overall goal of this patchset is to add a latency histogram which measures
> `mmap_lock` acquisition time. This is useful to measure the impact of ongoing
> work like maple trees and range locks (https://lwn.net/Articles/787629/), and
> it is also useful to debug userspace processes which experience long waits due
> to lock contention.
>
> This patchset is built upon walken@google.com's new `mmap_lock` API
> (https://lkml.org/lkml/2020/4/21/1307). In its current form, it should apply
> cleanly to a 5.7-rc7 tree to which Michel's patchset has already been applied.
>
> To summarize the changes being made at a high level:
>
> - Add a histogram library: a `struct histogram` is effectively an array of
> thresholds (i.e., buckets), and an array of per-cpu `u64` counts of the
> number of samples in each bucket.
this is maybe a redundant question as I did not follow the V1
submission.
Why do we need yet another histogram mechanism for instrumentation
purposes?
ftrace has histogram support already. Why can't this be reused?
Thanks,
tglx
prev parent reply other threads:[~2020-05-29 5:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 23:52 Axel Rasmussen
2020-05-29 0:24 ` Steven Rostedt
2020-05-29 1:39 ` Axel Rasmussen
2020-05-29 8:09 ` Peter Zijlstra
2020-05-29 15:03 ` Masami Hiramatsu
2020-05-29 22:38 ` Axel Rasmussen
2020-05-29 5:32 ` Thomas Gleixner [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87wo4vmhlq.fsf@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=Liam.Howlett@oracle.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=ardb@kernel.org \
--cc=avagin@gmail.com \
--cc=axelrasmussen@google.com \
--cc=brendanhiggins@google.com \
--cc=chenqiwu@xiaomi.com \
--cc=christian.brauner@ubuntu.com \
--cc=christian@kellner.me \
--cc=clabbe@baylibre.com \
--cc=cyphar@cyphar.com \
--cc=dan.j.williams@intel.com \
--cc=daniel.m.jordan@oracle.com \
--cc=davem@davemloft.net \
--cc=davidgow@google.com \
--cc=dbueso@suse.de \
--cc=ebiederm@xmission.com \
--cc=esyr@redhat.com \
--cc=glider@google.com \
--cc=guro@fb.com \
--cc=jamieliu@google.com \
--cc=jgg@ziepe.ca \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=john.garry@huawei.com \
--cc=junaids@google.com \
--cc=jwadams@google.com \
--cc=keescook@chromium.org \
--cc=khlebnikov@yandex-team.ru \
--cc=kirill.shutemov@linux.intel.com \
--cc=krzk@kernel.org \
--cc=ldufour@linux.ibm.com \
--cc=ldv@altlinux.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=mhiramat@kernel.org \
--cc=mhocko@suse.com \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=rcampbell@nvidia.com \
--cc=rdunlap@infradead.org \
--cc=rientjes@google.com \
--cc=rostedt@goodmis.org \
--cc=shakeelb@google.com \
--cc=takahiro.akashi@linaro.org \
--cc=talgi@mellanox.com \
--cc=uwe@kleine-koenig.org \
--cc=vbabka@suse.cz \
--cc=vincenzo.frascino@arm.com \
--cc=viro@zeniv.linux.org.uk \
--cc=walken@google.com \
--cc=will@kernel.org \
--cc=willy@infradead.org \
--cc=yamada.masahiro@socionext.com \
--cc=yang.shi@linux.alibaba.com \
--cc=yuzhao@google.com \
--cc=zaslonko@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox