From: Jeff Hostetler <git@jeffhostetler.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Derrick Stolee <stolee@gmail.com>,
Matheus Tavares <matheus.bernardino@usp.br>,
Johannes Sixt <j6t@kdbg.org>,
Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v2 5/9] trace2: add thread-name override to perf target
Date: Wed, 29 Dec 2021 12:15:43 -0500 [thread overview]
Message-ID: <0ac9ce53-55d0-624d-8386-47b2243cfbd6@jeffhostetler.com> (raw)
In-Reply-To: <211229.86ilv8gos7.gmgdl@evledraar.gmail.com>
On 12/28/21 8:48 PM, Ævar Arnfjörð Bjarmason wrote:
>
> On Tue, Dec 28 2021, Jeff Hostetler via GitGitGadget wrote:
>
>> From: Jeff Hostetler <jeffhost@microsoft.com>
>>
>> Teach the message formatter in the Trace2 perf target to accept an
>> optional thread name argument. This will override the thread name
>> inherited from the thread local storage data block.
>>
>> This will be used in a future commit for global events that should
>> not be tied to a particular thread, such as a global stopwatch timer.
>
> We already have a "ctx", and that "ctx" has a "thread_name", but here
> and in the preceding commit we're adding a "thread_name" to every caller
> of these functions in case we'd like to override it.
>
> Wouldn't it make more sense to just pass a "ctx" to these functions? One
> of them already takes it, here's an (obviously incomplete) fixup on top
> of your series to make the one that doesn't take a "ctx", and for the
> only non-NULL users of "thread_name" to just use a trivial helper to
> pass in a "ctx" with a new "thread_name", then to swap it back.
>
> It would make for a smaller diffstat for this already large series, or
> we could do exactly what we're doing now, but avoid the churn of
> adjusting every caller by introducing a new sister function for those
> who want this parameter to be non-NULL.
I suppose it is possible to have a helper version of
`event_fmt_prepare()` that takes the extra argument and
fixup the existing function to call it with NULL.
I'll see if that makes sense.
[...]
>
> +static void event_fmt_prepare_tn(const char *event_name, const char *file,
> + int line, const struct repository *repo,
> + struct json_writer *jw,
> + const char *thread_name)
> +{
> + struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
> + const char *tmp;
> +
> + tmp = ctx->thread_name;
> + ctx->thread_name = thread_name;
> + event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, jw, ctx);
> + ctx->thread_name = tmp;
> +}
[...]
This only works if we agree that thread name is a pointer inside
the structure and not a flex-array.
Personally, I think this is trying to do things backwards by
temporarily changing the ctx->thread_name field. I think it
would be better to `event_fmt_prepare_tn()` do the actual
work with the supplied thread name and have the existing
`event_fmt_prepare()` just call it with ctx->thread_name.
Then we don't need to hack up the ctx.
I'll see if this makes the diffs a little cleaner.
Jeff
next prev parent reply other threads:[~2021-12-29 17:15 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 ` [PATCH 0/9] Trace2 stopwatch timers and " Derrick Stolee
2021-12-21 23:27 ` 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 [this message]
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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