From: Derrick Stolee <stolee@gmail.com>
To: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org
Cc: Jeff Hostetler <jeffhost@microsoft.com>,
Matheus Tavares Bernardino <matheus.bernardino@usp.br>
Subject: Re: [PATCH 0/9] Trace2 stopwatch timers and global counters
Date: Tue, 21 Dec 2021 09:51:31 -0500 [thread overview]
Message-ID: <92923ca0-fbf9-e763-5735-214f3ad0cc3a@gmail.com> (raw)
In-Reply-To: <pull.1099.git.1640012469.gitgitgadget@gmail.com>
On 12/20/2021 10:01 AM, Jeff Hostetler via GitGitGadget wrote:
> Extend Trace2 to provide multiple "stopwatch timers" and "global counters".
> 3. Rationale
>
> Timers and counters are an alternative to the existing "region" and "data"
> events. The latter are intended to trace the major flow (or phases) of the
> program and possibly capture the amount of work performed within a loop, for
> example. The former are offered as a way to measure activity that is not
> localized, such as the time spent in zlib or lstat, which may be called from
> many different parts of the program.
>
> There are currently several places in the Git code where we want to measure
> such activity -- changed-path Bloom filter stats, topo-walk commit counts,
> and tree-walk counts and max-depths. A conversation in [1] suggested that we
> should investigate a more general mechanism to collect stats so that each
> instance doesn't need to recreate their own atexit handling mechanism.
>
> This is an attempt to address that and let us easily explore other areas in
> the future.
>
> This patch series does not attempt to refactor those three instances to use
> the new timers and counters. That should be a separate effort -- in part
> because we may want to retool them rather than just translate them. For
> example, rather than just translating the existing four Bloom filter counts
> (in revision.c) into Trace2 counters, we may instead want to have a "happy
> path timer" and a "sad path timer" if that would provide more insight.
I'm excited for these API features. It might be nice to have an RFC-
quality series demonstrating how these examples could work with the
new API. Makes sense to delay in case there were recommended changes
to the API from review in this v1.
I also like your attention to thread contexts. I think these timers
would be very interesting to use in parallel checkout. CC'ing Matheus
for his thoughts on where he would want timer summaries for that
feature. I would probably want the per-thread summary to know if we
are blocked on one really long thread while the others finish quickly.
Within that: what are the things causing us to be slow? Is it zlib?
Is it lstat()?
Thanks,
-Stolee
next prev parent reply other threads:[~2021-12-21 14:51 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 15:01 [PATCH 0/9] Trace2 stopwatch timers and global counters Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to char* Jeff Hostetler via GitGitGadget
2021-12-20 16:31 ` Ævar Arnfjörð Bjarmason
2021-12-20 19:07 ` Jeff Hostetler
2021-12-20 19:35 ` Ævar Arnfjörð Bjarmason
2021-12-22 16:32 ` Jeff Hostetler
2021-12-21 7:33 ` Junio C Hamano
2021-12-21 7:22 ` Junio C Hamano
2021-12-22 16:28 ` Jeff Hostetler
2021-12-22 19:57 ` Junio C Hamano
2021-12-20 15:01 ` [PATCH 3/9] trace2: defer free of TLS CTX until program exit Jeff Hostetler via GitGitGadget
2021-12-21 7:30 ` Junio C Hamano
2021-12-22 21:59 ` Jeff Hostetler
2021-12-22 22:56 ` Junio C Hamano
2021-12-22 23:04 ` Jeff Hostetler
2021-12-23 7:38 ` Johannes Sixt
2021-12-23 18:18 ` Junio C Hamano
2021-12-27 18:51 ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:39 ` Ævar Arnfjörð Bjarmason
2021-12-20 19:44 ` Jeff Hostetler
2021-12-21 14:20 ` Derrick Stolee
2021-12-20 15:01 ` [PATCH 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-20 16:42 ` Ævar Arnfjörð Bjarmason
2021-12-22 21:38 ` Jeff Hostetler
2021-12-21 14:45 ` Derrick Stolee
2021-12-22 21:57 ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:51 ` Ævar Arnfjörð Bjarmason
2021-12-22 22:56 ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-20 17:14 ` Ævar Arnfjörð Bjarmason
2021-12-22 22:18 ` Jeff Hostetler
2021-12-21 14:51 ` Derrick Stolee [this message]
2021-12-21 23:27 ` [PATCH 0/9] Trace2 stopwatch timers and " Matheus Tavares
2021-12-28 19:36 ` [PATCH v2 " Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-29 0:48 ` Ævar Arnfjörð Bjarmason
2021-12-28 19:36 ` [PATCH v2 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to flex array Jeff Hostetler via GitGitGadget
2021-12-29 1:11 ` Ævar Arnfjörð Bjarmason
2021-12-29 16:46 ` Jeff Hostetler
2021-12-28 19:36 ` [PATCH v2 3/9] trace2: defer free of thread local storage until program exit Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-29 1:48 ` Ævar Arnfjörð Bjarmason
2021-12-29 17:15 ` Jeff Hostetler
2021-12-28 19:36 ` [PATCH v2 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36 ` [PATCH v2 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-29 1:54 ` [PATCH v2 0/9] Trace2 stopwatch timers and " Ævar Arnfjörð Bjarmason
2021-12-30 16:42 ` Jeff Hostetler
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