Message-ID: <557AFDB1.7030902@gmail.com>
Date: Fri, 12 Jun 2015 09:41:37 -0600
From: David Ahern <dsahern@gmail.com>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: "Liang, Kan" <kan.liang@intel.com>, Andi Kleen <andi@firstfloor.org>
CC: Arnaldo Carvalho de Melo <acme@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Huang, Ying" <ying.huang@intel.com>
Subject: Re: [PATCH 1/1] perf,tools: add time out to force stop endless mmap
 processing
References: <1433922364-22580-1-git-send-email-kan.liang@intel.com> <20150611140614.GC2696@kernel.org> <5579A766.4010504@gmail.com> <20150611184737.GU19417@two.firstfloor.org> <557A28F6.8040603@gmail.com> <37D7C6CF3E00A74B8858931C1DB2F077018767AD@SHSMSX103.ccr.corp.intel.com>
In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F077018767AD@SHSMSX103.ccr.corp.intel.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1570
Lines: 38

On 6/12/15 8:42 AM, Liang, Kan wrote:
>
>>
>> On 6/11/15 12:47 PM, Andi Kleen wrote:
>>>> Can you elaborate on an example? I don't see how this can happen
>>>> reading a maps file. And it does not read maps for all threads only
>>>> thread group leaders.
>>>
>>> This is with a stress test case that generates lots of small mappings
>>> at very high speed and frees them again. So the maps file keeps
>>> changing faster than the proc reader can keep it and it can end up
>>> with a live lock.
>>
>> Can you pass it along? I'd like to see how the task_diag proposal handles it.
>>
>> https://github.com/dsahern/linux/commits/task_diag-wip
>
> Hi David,
>
> I tried the task_diag on my platform, but it shows error message when I
> run perf top. " Message handling failed: rc -1, errno 25".
> And it looks perf top failed to get maps information.

Not surprising; it's only half-baked. Can you try perf-record? So far 
that is the only one I have tested.

Also, while running that kernel you can build the test programs under 
tools/testing/selftests/task_diag/ and try task_diag_all. I am away from 
my dev box at the moment. As I recall you will want to try 
'task_diag_all o $pid' or 'task_diag_all a'

I take this to mean you don't want to share the test program? I am 
curious as to how other tools handle this use case.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/