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From: Jeff Moyer <jmoyer@redhat.com>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] direct-io: Deinline submit_page_section, save 5304 bytes
Date: Mon, 14 Mar 2016 10:36:10 -0400	[thread overview]
Message-ID: <x4960wpunxh.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <1457902836-30786-1-git-send-email-dvlasenk@redhat.com> (Denys Vlasenko's message of "Sun, 13 Mar 2016 22:00:34 +0100")

Denys Vlasenko <dvlasenk@redhat.com> writes:

> This function compiles to 2628 bytes, 2 callsites
>
>    text	   data	    bss	    dec	    hex	filename
>   15197	     16	      0	  15213	   3b6d	direct-io.o.before1
>    9655	     16	      0	   9671	   25c7	direct-io.o

And what is the consequence for performance?  If you look at the git
history for this file, you'll find the commit that introduced the
inline:

commit ba253fbf6d3502c54e1ac8792e7ac8290a1f5b8d
Author: Andi Kleen <ak@linux.intel.com>
Date:   Mon Aug 1 21:38:08 2011 -0700

    direct-io: inline the complete submission path
    
    Add inlines to all the submission path functions. While this increases
    code size it also gives gcc a lot of optimization opportunities
    in this critical hotpath.

    ...

So you're essentially undoing that work.

NAK

Cheers,
Jeff

      parent reply	other threads:[~2016-03-14 14:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-13 21:00 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
2016-03-13 21:00 ` [PATCH] direct-io: Deinline dio_send_cur_page, save ~2000 bytes Denys Vlasenko
2016-03-14 14:37   ` Jeff Moyer
2016-03-14 14:36 ` Jeff Moyer [this message]

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