From: David Ahern <dsahern@gmail.com>
To: Shaohua Li <shli@fb.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>,
Kernel-team@fb.com, "H. Peter Anvin" <hpa@zytor.com>,
Ingo Molnar <mingo@redhat.com>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH v2 3/3] X86: Add a thread cpu time implementation to vDSO
Date: Fri, 02 Jan 2015 08:31:33 -0700 [thread overview]
Message-ID: <54A6B9D5.5040804@gmail.com> (raw)
In-Reply-To: <20150102025953.GA1253265@devbig257.prn2.facebook.com>
On 1/1/15 7:59 PM, Shaohua Li wrote:
> I'm wondering how we could use the perf to implament a clock_gettime.
> reading the perf fd or using ioctl is slow so reading the mmap
> ringbuffer is the only option. But as far as I know the ringbuffer has
> data only when an event is generated. Between two events, there is
> nothing we can read from the ringbuffer. Then how can application get
> time info in the interval?
Are you wanting to read perf_clock from userspace?
David
next prev parent reply other threads:[~2015-01-02 15:31 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-17 23:12 [PATCH v2 1/3] X86: make VDSO data support multiple pages Shaohua Li
2014-12-17 23:12 ` [PATCH v2 2/3] X86: add a generic API to let vdso code detect context switch Shaohua Li
2014-12-19 1:05 ` Thomas Gleixner
2014-12-17 23:12 ` [PATCH v2 3/3] X86: Add a thread cpu time implementation to vDSO Shaohua Li
2014-12-18 23:30 ` Andy Lutomirski
2014-12-19 0:22 ` Andy Lutomirski
2014-12-19 0:30 ` Shaohua Li
2014-12-19 0:32 ` Andy Lutomirski
2014-12-19 0:34 ` Thomas Gleixner
2014-12-19 11:23 ` Peter Zijlstra
2014-12-19 16:48 ` Andy Lutomirski
2014-12-19 17:03 ` Peter Zijlstra
2014-12-19 17:07 ` Andy Lutomirski
2014-12-19 17:27 ` Peter Zijlstra
2014-12-19 17:42 ` Andy Lutomirski
2015-01-02 2:59 ` Shaohua Li
2015-01-02 15:31 ` David Ahern [this message]
2015-01-02 17:02 ` Shaohua Li
2015-01-02 17:09 ` David Ahern
2015-01-02 17:17 ` Shaohua Li
2015-01-02 17:26 ` David Ahern
2015-01-02 17:47 ` Andy Lutomirski
2015-01-05 23:23 ` Shaohua Li
2015-01-06 10:18 ` Peter Zijlstra
2015-01-06 16:59 ` Shaohua Li
2015-01-12 19:50 ` Shaohua Li
2014-12-19 17:42 ` Chris Mason
2014-12-19 17:53 ` Andy Lutomirski
2014-12-19 18:16 ` Shaohua Li
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