From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: open list <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
"acme@kernel.org" <acme@kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@kernel.org>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v6] perf: Sharing PMU counters across compatible events
Date: Wed, 6 Nov 2019 09:56:15 +0100 [thread overview]
Message-ID: <20191106085615.GW4114@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <FAD07921-FB10-4FDD-9A81-48300EE24F20@fb.com>
On Tue, Nov 05, 2019 at 11:51:42PM +0000, Song Liu wrote:
> > We allocate a separate perf_event for perf_event_dup->master. This needs
> > extra attention, because perf_event_alloc() may sleep. To allocate the
> > master event properly, a new pointer, tmp_master, is added to perf_event.
> > tmp_master carries a separate perf_event into list_[add|del]_event().
> > The master event has valid ->ctx and holds ctx->refcount.
>
> If we do GFP_ATOMIC in perf_event_alloc(), maybe with an extra option, we
> don't need the tmp_master hack. So we only allocate master when we will
> use it.
You can't, that's broken on -RT. ctx->lock is a raw_spinlock_t and
allocator locks are spinlock_t.
prev parent reply other threads:[~2019-11-06 8:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 5:23 Song Liu
2019-09-30 5:36 ` Song Liu
2019-10-31 12:43 ` Peter Zijlstra
2019-10-31 16:29 ` Song Liu
2019-11-05 17:11 ` Song Liu
2019-11-05 20:16 ` Peter Zijlstra
2019-11-05 23:06 ` Song Liu
2019-11-06 9:14 ` Peter Zijlstra
2019-11-06 17:40 ` Song Liu
2019-11-06 20:44 ` Peter Zijlstra
2019-11-06 22:23 ` Song Liu
2019-11-05 23:51 ` Song Liu
2019-11-06 8:56 ` Peter Zijlstra [this message]
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