Date: Fri, 18 Jan 2008 19:46:22 +0100
To: Arjan van de Ven <arjan@linux.intel.com>
From: Roberto Fichera <kernel@tekno-soft.it>
Subject: Re: [Announce] Development release 0.1 of the LatencyTOP tool
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>
In-Reply-To: <4790F172.5070907@linux.intel.com>
References: <4790E3A6.7060807@linux.intel.com>
 <20080118182714.2DA32498006@tavolara.isolaweb.it>
 <4790F172.5070907@linux.intel.com>
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At 19.35 18/01/2008, Arjan van de Ven wrote:
>Roberto Fichera wrote:
>> At 18.36 18/01/2008, Arjan van de Ven wrote:
>>> The Intel Open Source Technology Center is pleased to announce the
>>> release of version 0.1 of LatencyTOP, a tool for developers to visualize
>>> system latencies.
>>>
>>> http://www.latencytop.org
>>>
>> 
>> [...snip...]
>> 
>>> The most basic annotation looks like this (in the patches more complex
>>> versions can be seen):
>>>
>>>  asmlinkage long sys_sync(void)
>>>  {
>>> +       struct latency_entry reason;
>>> +       set_latency_reason("sync system call", &reason);
>>>         do_sync(1);
>>> +       restore_latency_reason(&reason);
>>> +
>>>         return 0;
>>>  }
>>>
>> 
>> I really like this patch :-)! Just a little note, why don't make 
>> the parameter 'char *reason' as simple integer (reason_t)? 
>> Making it as integer will automatically drop the strncmp() 
>> and speeding up all the things. Could be also interesting to 
>> define _externally_ the mapping of the reason so the 
>> userspace tool could handle it easily.
>> 
>
>I thought about that, but the strncmp is still somewhat needed to deal 
>with the argument
>(the instrumentation above doesn't use that, but the mutex one does 
>for example)
>If we get rid of the argument entirely it'd be easier
>(but then we get "blocking on mutex" rather than "blocking on inode->mutex")

Duh! I didn't notice it! Now I see ;-)!

>

Roberto Fichera. 

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