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From: Yi Sun <yi.sun@intel.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>, <dave.hansen@intel.com>,
	<linux-kernel@vger.kernel.org>, <x86@kernel.org>,
	<sohil.mehta@intel.com>, <ilpo.jarvinen@linux.intel.com>,
	<heng.su@intel.com>, <tony.luck@intel.com>,
	<yi.sun@linux.intel.com>, <yu.c.chen@intel.com>
Subject: Re: [PATCH v7 1/3] x86/fpu: Measure the Latency of XSAVE and XRSTOR
Date: Fri, 22 Sep 2023 11:44:18 +0800	[thread overview]
Message-ID: <ZQ0NkklaVzFgoeww@ysun46-mobl.ccr.corp.intel.com> (raw)
In-Reply-To: <ZQx01AfyvbJQYPsi@tassilo>

On 21.09.2023 09:52, Andi Kleen wrote:
>> It seems unnecessarily complex: why does it have to measure latency
>> directly? Tracepoints *by default* come with event timestamps. A latency
>> measurement tool should be able to subtract two timestamps to extract the
>> latency between two tracepoints...
>>
>> In fact, function tracing is enabled on all major Linux distros:
>>
>>   kepler:~/tip> grep FUNCTION_TRACER /boot/config-6.2.0-33-generic
>>   CONFIG_HAVE_FUNCTION_TRACER=y
>>   CONFIG_FUNCTION_TRACER=y
>>
>> Why not just enable function tracing for the affected FPU context switching
>> functions?
>
>Or use PT address filters to get it even accurately, as described
>in [1]. In any case I agree the trace points are not needed.
>
Hi Andi,

Here, we have implemented latency measurement for all x86 platforms, not
just for Intel but also for other vendors like AMD. This allows us to 
obtain comparable data.

Thanks
    --Sun, Yi

  reply	other threads:[~2023-09-22  3:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-21  6:28 [PATCH v7 0/3] x86/fpu Measure the Latency of XSAVES and XRSTORS Yi Sun
2023-09-21  6:28 ` [PATCH v7 1/3] x86/fpu: Measure the Latency of XSAVE and XRSTOR Yi Sun
2023-09-21  7:03   ` Ingo Molnar
2023-09-21  8:24     ` Yi Sun
2023-09-21 16:52     ` Andi Kleen
2023-09-22  3:44       ` Yi Sun [this message]
2023-09-21  6:28 ` [PATCH v7 2/3] tools/testing/fpu: Add script to consume trace log of xsave latency Yi Sun
2023-09-21  6:29 ` [PATCH v7 3/3] tools/testing/fpu: Add a 'count' column Yi Sun

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