From: Ming Lei <tom.leiming@gmail.com>
To: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>, Jens Axboe <axboe@fb.com>,
Christoph Hellwig <hch@lst.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] direct-io: Deinline dio_zero_block, save 2684 bytes
Date: Mon, 14 Mar 2016 09:07:12 +0800 [thread overview]
Message-ID: <CACVXFVPnUY10wyezv4JudXAFyrZtBzk5UYAevZEOc-ht=TupMg@mail.gmail.com> (raw)
In-Reply-To: <CAK1hOcOLJ_BHwJv-=ABrf9Rpycm+ppTA-DpOxF+kKbF-35BgYg@mail.gmail.com>
On Mon, Mar 14, 2016 at 5:36 AM, Denys Vlasenko
<vda.linux@googlemail.com> wrote:
> On Sun, Mar 13, 2016 at 10:00 PM, Denys Vlasenko <dvlasenk@redhat.com> wrote:
>> This function compiles to 2684 bytes, 2 callsites
>>
>> text data bss dec hex filename
>> 9655 16 0 9671 25c7 direct-io.o.before2
>> 9559 16 0 9575 2567 direct-io.o
>
> Al, you undoubtedly noticed the discrepancy between
> "save 2684 bytes" claim in the commit description
> and the above data, which shows no such thing.
>
> Sorry, I was too quick to send the mail to notice it :(
>
> Further investigation had shown that it's my particular version of gcc
> deciding to deinline the function even before the patch.
> Other version of gcc, on a different machine was running
> large inlining search script, did not do that, and saw the 2684 bytes
> of savings.
>
> tl;dr: the patch is correct, my "size" printout wasn't.
Not sure the patch is correct, please see the commit for
do_blockdev_direct_IO():
* NOTE: if you pass "sdio" to anything by pointer make sure that function
* is always inlined. Otherwise gcc is unable to split the structure into
* individual fields and will generate much worse code. This is important
* for the whole file.
thanks,
Ming Lei
next prev parent reply other threads:[~2016-03-14 1:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-13 21:36 [PATCH] direct-io: Deinline dio_zero_block, save 2684 bytes Denys Vlasenko
2016-03-14 1:07 ` Ming Lei [this message]
-- strict thread matches above, loose matches on Subject: below --
2016-03-13 21:00 [PATCH] direct-io: Deinline submit_page_section, save 5304 bytes Denys Vlasenko
2016-03-13 21:00 ` [PATCH] direct-io: Deinline dio_zero_block, save 2684 bytes Denys Vlasenko
2016-03-14 14:37 ` Jeff Moyer
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