From: Pavel Begunkov <asml.silence@gmail.com>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"target-devel@vger.kernel.org" <target-devel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] target/file: don't zero iter before iov_iter_bvec
Date: Mon, 11 Jan 2021 02:28:52 +0000 [thread overview]
Message-ID: <68887abc-2ef4-035e-625b-84569c1b5b24@gmail.com> (raw)
In-Reply-To: <BYAPR04MB4965E008861D5B29B9E757D186AB0@BYAPR04MB4965.namprd04.prod.outlook.com>
On 11/01/2021 02:06, Chaitanya Kulkarni wrote:
> On 1/9/21 13:29, Pavel Begunkov wrote:
>> On 09/01/2021 20:52, Chaitanya Kulkarni wrote:
>>> On 1/9/21 12:40, Pavel Begunkov wrote:
>>>> I expect you won't find any, but such little things can pile up
>>>> into a not-easy-to-spot overhead over time.
>>> That is what I suspected with the resulting assembly. The commit log
>>> needs to document that there is no direct impact on the performance
>> It's obvious that 3-4 extra mov $0 off(%reg) won't change performance
>> but still hasn't been formally confirmed ...
> This is obvious for you and me since we spent time into looking into
> resulting assembly not every reviewer is expected to do that see [1].
>>
>>> which can be seen with this patch, but this is nice to have
>> ... so if you don't mind, I won't be resending just for that.
> As per commit log guidelines [1] you have to quantify the optimization.
>
> Since you cannot quantify the optimization modify the commit log explaining
And then you see "Optimizations usually aren’t free but trade-offs
between", and the patch doesn't fall under it.
Let me be frank, I see it more like as a whim. If the maintainer agrees
with that strange requirement of yours and want to bury it under
bureaucracy, fine by me, don't take it, I don't care, but I haven't
ever been asked here to do that for patches as this.
> that there is not significant performance benefit observe.
It's not "I cannot" but rather "I haven't even tried to and expect...".
Don't mix, there is a huge difference between.
--
Pavel Begunkov
next prev parent reply other threads:[~2021-01-11 2:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 15:53 [PATCH] target/file: don't zero iter before iov_iter_bvec Pavel Begunkov
2021-01-09 20:09 ` Chaitanya Kulkarni
2021-01-09 20:37 ` Pavel Begunkov
2021-01-09 20:52 ` Chaitanya Kulkarni
2021-01-09 21:25 ` Pavel Begunkov
2021-01-11 2:06 ` Chaitanya Kulkarni
2021-01-11 2:28 ` Pavel Begunkov [this message]
2021-01-11 5:23 ` Chaitanya Kulkarni
2021-01-11 5:31 ` Pavel Begunkov
2021-01-11 2:49 ` Bart Van Assche
2021-01-13 5:34 ` Martin K. Petersen
2021-01-15 4:08 ` Martin K. Petersen
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