linux-kernel - Re: [PATCH v2] fs: introduce is_dot

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Message-ID: <b3f23eef-3799-6ddd-43ba-11a90f49279d@loongson.cn>
Date:   Thu, 5 Dec 2019 15:55:50 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <yuchao0@...wei.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Tyler Hicks <tyhicks@...onical.com>,
        linux-fsdevel@...r.kernel.org, ecryptfs@...r.kernel.org,
        linux-fscrypt@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] fs: introduce is_dot_dotdot helper for cleanup

On 12/05/2019 03:06 PM, Matthew Wilcox wrote:
> On Thu, Dec 05, 2019 at 08:56:07AM +0800, Tiezhu Yang wrote:
>>> And, as I asked twice in the last round of review, did you benchmark
>>> this change?
>> Before sending this v2 patch, I have done the test used with your test
>> program and already pointed out the following implementation is better:
> I didn't mean "have you run the test program i wrote".  I meant "have you
> booted a kernel with this change and done some performance measurements
> to see if you've changed anything".

Oh, no, it is hard to measure the performance influence with this patch.
Based on the above analysis, I think the performance influence is very
small due to is_dot_dotdot() is a such short static inline function.

Thanks,

Tiezhu Yang