From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Jeff Hostetler <jeffhost@microsoft.com>,
Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
Subject: Re: [RFC PATCH] trace2 API: don't save a copy of constant "thread_name"
Date: Fri, 07 Oct 2022 12:03:45 +0200 [thread overview]
Message-ID: <221007.865ygvrjs7.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <xmqqo7uoh1q0.fsf@gitster.g>
On Thu, Oct 06 2022, Junio C Hamano wrote:
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>> A cleaned up version of the test code I had on top of "master", RFC
>> because I may still be missing some context here. E.g. maybe there's a
>> plan to dynamically construct these thread names?
>
> That's nice to learn, indeed.
>
>> +void jw_object_string_thread(struct json_writer *jw, const char *thread_name,
>> + int thread_id)
>> +{
>> + object_common(jw, "thread");
>> + strbuf_addch(&jw->json, '"');
>> + jw_strbuf_add_thread_name(&jw->json, thread_name, thread_id);
>> + strbuf_addch(&jw->json, '"');
>> +}
>
> ...
>
>> @@ -107,9 +109,11 @@ static void perf_fmt_prepare(const char *event_name,
>> }
>>
>> strbuf_addf(buf, "d%d | ", tr2_sid_depth());
>> - strbuf_addf(buf, "%-*s | %-*s | ", TR2_MAX_THREAD_NAME,
>> - ctx->thread_name.buf, TR2FMT_PERF_MAX_EVENT_NAME,
>> - event_name);
>> + oldlen = buf->len;
>> + jw_strbuf_add_thread_name(buf, ctx->thread_name, ctx->thread_id);
>> + padlen = TR2_MAX_THREAD_NAME - (buf->len - oldlen);;
>> + strbuf_addf(buf, "%-*s | %-*s | ", padlen, "",
>> + TR2FMT_PERF_MAX_EVENT_NAME, event_name);
>
> Having to do strbuf_addf() many times may negatively affect perf_*
> stuff, if this code is invoked in the hot path. I however tend to
> treat anything that involves an I/O not performance critical, and
> this certainly falls into that category.
Yes, and that function already called strbuf_addf() 5-7 times, this adds
one more, but only if "thread_id" is > 0.
The reason I added jw_object_string_thread() was to avoid the malloc() &
free() of a temporary "struct strbuf", it would have been more
straightforward to call jw_object_string() like that.
I don't think anyone cares about the raw performance of the "perf"
output, but the "JSON" one needs to be fast(er).
But even that output will malloc()/free() for each line it emits, and
often multiple times within one line (e.g. each time we format a
double).
So if we do want to optimize this in terms of memory use the lowest
hanging fruit seems to be to just have a per-thread "scratch" buffer
we'd write to, we could also observe that we're writing to a file and
just directly write to it in most cases (although we'd need to be
careful to write partial-and-still-invalid JSON lines in that case...).
next prev parent reply other threads:[~2022-10-07 10:49 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-04 16:19 [PATCH 0/9] Trace2 timers and counters and some cleanup Jeff Hostetler via GitGitGadget
2022-10-04 16:19 ` [PATCH 1/9] builtin/merge-file: fix compiler warning on MacOS with clang 11.0.0 Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 2/9] builtin/unpack-objects.c: " Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 3/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 4/9] tr2tls: clarify TLS terminology Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 5/9] trace2: rename trace2 thread_name argument as name_hint Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 6/9] trace2: convert ctx.thread_name to flex array Jeff Hostetler via GitGitGadget
2022-10-05 11:14 ` Ævar Arnfjörð Bjarmason
2022-10-06 16:28 ` Jeff Hostetler
2022-10-10 18:31 ` Jeff Hostetler
2022-10-05 18:03 ` Junio C Hamano
2022-10-06 21:05 ` Ævar Arnfjörð Bjarmason
2022-10-06 21:50 ` Junio C Hamano
2022-10-07 1:10 ` [RFC PATCH] trace2 API: don't save a copy of constant "thread_name" Ævar Arnfjörð Bjarmason
2022-10-07 1:16 ` Junio C Hamano
2022-10-07 10:03 ` Ævar Arnfjörð Bjarmason [this message]
2022-10-10 19:16 ` Jeff Hostetler
2022-10-11 13:31 ` Ævar Arnfjörð Bjarmason
2022-10-12 13:31 ` Jeff Hostetler
2022-10-10 19:05 ` Jeff Hostetler
2022-10-11 12:52 ` Ævar Arnfjörð Bjarmason
2022-10-11 14:40 ` Junio C Hamano
2022-10-10 18:39 ` [PATCH 6/9] trace2: convert ctx.thread_name to flex array Jeff Hostetler
2022-10-04 16:20 ` [PATCH 7/9] api-trace2.txt: elminate section describing the public trace2 API Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 8/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2022-10-04 16:20 ` [PATCH 9/9] trace2: add global counter mechanism Jeff Hostetler via GitGitGadget
2022-10-05 13:04 ` [PATCH 0/9] Trace2 timers and counters and some cleanup Ævar Arnfjörð Bjarmason
2022-10-06 15:45 ` Jeff Hostetler
2022-10-06 18:12 ` Derrick Stolee
2022-10-12 18:52 ` [PATCH v2 0/7] " Jeff Hostetler via GitGitGadget
2022-10-12 18:52 ` [PATCH v2 1/7] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2022-10-12 18:52 ` [PATCH v2 2/7] tr2tls: clarify TLS terminology Jeff Hostetler via GitGitGadget
2022-10-13 21:12 ` Junio C Hamano
2022-10-12 18:52 ` [PATCH v2 3/7] api-trace2.txt: elminate section describing the public trace2 API Jeff Hostetler via GitGitGadget
2022-10-12 18:52 ` [PATCH v2 4/7] trace2: rename the thread_name argument to trace2_thread_start Jeff Hostetler via GitGitGadget
2022-10-12 21:06 ` Ævar Arnfjörð Bjarmason
2022-10-20 14:40 ` Jeff Hostetler
2022-10-13 21:12 ` Junio C Hamano
2022-10-12 18:52 ` [PATCH v2 5/7] trace2: convert ctx.thread_name from strbuf to pointer Jeff Hostetler via GitGitGadget
2022-10-13 21:12 ` Junio C Hamano
2022-10-12 18:52 ` [PATCH v2 6/7] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2022-10-13 21:12 ` Junio C Hamano
2022-10-20 14:42 ` Jeff Hostetler
2022-10-12 18:52 ` [PATCH v2 7/7] trace2: add global counter mechanism Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 0/8] Trace2 timers and counters and some cleanup Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 1/8] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 2/8] tr2tls: clarify TLS terminology Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 3/8] api-trace2.txt: elminate section describing the public trace2 API Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 4/8] trace2: rename the thread_name argument to trace2_thread_start Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 5/8] trace2: improve thread-name documentation in the thread-context Jeff Hostetler via GitGitGadget
2022-10-20 18:57 ` Ævar Arnfjörð Bjarmason
2022-10-20 20:15 ` Jeff Hostetler
2022-10-20 18:28 ` [PATCH v3 6/8] trace2: convert ctx.thread_name from strbuf to pointer Jeff Hostetler via GitGitGadget
2022-10-20 18:28 ` [PATCH v3 7/8] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2022-10-20 20:25 ` Junio C Hamano
2022-10-20 20:52 ` Jeff Hostetler
2022-10-20 20:55 ` Junio C Hamano
2022-10-21 21:51 ` Jeff Hostetler
2022-10-20 18:28 ` [PATCH v3 8/8] trace2: add global counter mechanism Jeff Hostetler via GitGitGadget
2022-10-24 13:40 ` [PATCH v4 0/8] Trace2 timers and counters and some cleanup Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 1/8] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2022-10-24 20:31 ` Junio C Hamano
2022-10-25 12:35 ` Derrick Stolee
2022-10-25 15:40 ` Junio C Hamano
2022-10-24 13:41 ` [PATCH v4 2/8] tr2tls: clarify TLS terminology Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 3/8] api-trace2.txt: elminate section describing the public trace2 API Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 4/8] trace2: rename the thread_name argument to trace2_thread_start Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 5/8] trace2: improve thread-name documentation in the thread-context Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 6/8] trace2: convert ctx.thread_name from strbuf to pointer Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 7/8] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2022-10-24 13:41 ` [PATCH v4 8/8] trace2: add global counter mechanism Jeff Hostetler via GitGitGadget
2022-10-25 12:27 ` [PATCH v4 0/8] Trace2 timers and counters and some cleanup Derrick Stolee
2022-10-25 15:36 ` Junio C Hamano
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