From: Weng Meiling <wengmeiling.weng@huawei.com>
To: Will Deacon <will.deacon@arm.com>, Robert Richter <rric@kernel.org>
Cc: "oprofile-list@lists.sf.net" <oprofile-list@lists.sf.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Li Zefan <lizefan@huawei.com>,
"wangnan0@huawei.com" <wangnan0@huawei.com>,
"zhangwei(Jovi)" <jovi.zhangwei@huawei.com>,
Huang Qiang <h.huangqiang@huawei.com>,
"sdu.liu@huawei.com" <sdu.liu@huawei.com>
Subject: Re: [PATCH] oprofile: check whether oprofile perf enabled in op_overflow_handler()
Date: Fri, 17 Jan 2014 11:37:19 +0800 [thread overview]
Message-ID: <52D8A56F.1010507@huawei.com> (raw)
In-Reply-To: <20140116193652.GD22105@mudshark.cambridge.arm.com>
On 2014/1/17 3:36, Will Deacon wrote:
> On Thu, Jan 16, 2014 at 11:52:45AM +0000, Robert Richter wrote:
>> (cc'ing Will)
>
> Thanks Robert,
>
>> The problem of too low sample periods could be solved on ARM by using
>> perf's interrupt throttling, you might play around with:
>>
>> /proc/sys/kernel/perf_event_max_sample_rate:100000
>>
>> I am not quite sure whether this works esp. for kernel counters and
Try to lower the value of perf_event_max_sample_rate, it works. Testing
the following values:
100 500 1000 5000 10000 50000
for the last value, the command start to stall.
Just a simple test. :)
>> how userland can be notified about throttling. Throttling could be
>> worth for operf too, not only for the oprofile kernel driver.
>>
>> From a quick look it seems there is also code in x86 that dynamically
>> adjusts the rate which might be worth being implemented for ARM too.
>
> Are you referring to the perf_sample_event_took callback? If so, that
> certainly looks worth persuing. I'll stick it on my list, thanks!
>
Thanks Will for doing this.
Thanks
Weng Meiling
> Will
>
> .
>
next prev parent reply other threads:[~2014-01-17 3:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-20 7:49 [PATCH] oprofile: check whether oprofile perf enabled in op_overflow_handler() Weng Meiling
2013-12-30 9:06 ` Weng Meiling
2014-01-13 8:45 ` Robert Richter
2014-01-14 1:52 ` Weng Meiling
2014-01-14 15:05 ` Robert Richter
2014-01-15 2:02 ` Weng Meiling
2014-01-15 10:24 ` Robert Richter
2014-01-16 1:09 ` Weng Meiling
2014-01-16 9:33 ` Weng Meiling
2014-01-16 11:52 ` Robert Richter
2014-01-16 19:36 ` Will Deacon
2014-01-17 3:37 ` Weng Meiling [this message]
2014-02-11 4:33 ` Weng Meiling
2014-02-11 15:52 ` Will Deacon
2014-02-11 18:05 ` Will Deacon
2014-02-15 2:41 ` Weng Meiling
2014-02-17 10:08 ` Will Deacon
2014-02-17 11:39 ` Weng Meiling
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