linux-kernel - Re: [PATCH v2] perf top: expand the range of multithreaded phase

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Message-ID: <edec17ee-2a10-bdb1-a021-180831bbc57c@huawei.com>
Date:   Mon, 10 Apr 2023 11:38:07 +0800
From:   "Wenyu Liu(D)" <liuwenyu7@...wei.com>
To:     Hangliang Lai <laihangliang1@...wei.com>, <namhyung@...nel.org>
CC:     <acme@...nel.org>, <adrian.hunter@...el.com>,
        <alexander.shishkin@...ux.intel.com>, <brauner@...nel.org>,
        <hewenliang4@...wei.com>, <irogers@...gle.com>, <jolsa@...nel.org>,
        <linfeilong@...wei.com>, <linux-kernel@...r.kernel.org>,
        <linux-perf-users@...r.kernel.org>, <mark.rutland@....com>,
        <mingo@...hat.com>, <yeyunfeng@...wei.com>
Subject: Re: [PATCH v2] perf top: expand the range of multithreaded phase

Hello，I think Namhyung means only make it multi-threaded unconditionally after the synthesize

a patch like this:

---
 tools/perf/builtin-top.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d4b5b02bab73..60d00975b881 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1273,8 +1273,7 @@ static int __cmd_top(struct perf_top *top)
                                    top->evlist->core.threads, true, false,
                                    top->nr_threads_synthesize);

-       if (top->nr_threads_synthesize > 1)
-               perf_set_singlethreaded();
+       perf_set_multithreaded();

        if (perf_hpp_list.socket) {
                ret = perf_env__read_cpu_topology_map(&perf_env);
--

Right?

Thanks,
Wenyu

在 2023/4/10 10:58, Hangliang Lai 写道:
> Thanks for your reply Kim ,
> 
> 
> 
> On 2023-04-07 21:21   you  wrote:
> 
> 
> 
>>  Not always, the synthesis can run in a single thread.
> 
> 
> 
> But I think in machine__synthesize_threads, there are thread_nr threads will be created to do synthesize_threads_worker(tools/perf/util/synthetic-events.c:970)
> 
> 
> 
> It’s not a single thread part. So we're supposed to call perf_set_multithreaded() before synthesize?
> 
> 
> 
> Thanks,
> 
> Hangliang Lai
> 
> 
>