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From: Andy Lutomirski <luto@amacapital.net>
To: Jan Kara <jack@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/3] Add madvise(..., MADV_WILLWRITE)
Date: Thu, 8 Aug 2013 17:11:30 -0700	[thread overview]
Message-ID: <CALCETrVZBpZDQ7-QjDYYQyGGtCEAk-ydb0DUUA9gcFtj4JYv6w@mail.gmail.com> (raw)
In-Reply-To: <CALCETrVXTXzXAmUsmmWxwr6vK+Vux7_pUzWPYyHjxEbn3ObABg@mail.gmail.com>

On Thu, Aug 8, 2013 at 12:25 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>
> Whoops -- I read your email too quickly.  I haven't tried
> MADV_WILLNEED, but I think I tried reading each page to fault them in.
>  Is there any reason to expect MADV_WILLNEED to do any better?  I'll
> try to do some new tests to see how well this all works.
>
> (I imagine that freshly fallocated files are somehow different when
> read, since there aren't zeros on the disk backing them until they get
> written.)

Well, this will teach me to write code based on an old benchmark from
memory.  It seems that prefaulting for read is okay on Linux 3.9 --
latencytop isn't do_wp_page or ext4* at all, at least not for the last
couple minutes on my test box.

I wonder if ext4 changed its handling of fallocated extents somewhere
between 3.5 and 3.9.  In any case, please consider these patches
withdrawn for the time being.

* With file_update_time stubbed out.  I need to dust off my old
patches to fix that part.

WARNING: multiple messages have this Message-ID (diff)
From: Andy Lutomirski <luto@amacapital.net>
To: Jan Kara <jack@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/3] Add madvise(..., MADV_WILLWRITE)
Date: Thu, 8 Aug 2013 17:11:30 -0700	[thread overview]
Message-ID: <CALCETrVZBpZDQ7-QjDYYQyGGtCEAk-ydb0DUUA9gcFtj4JYv6w@mail.gmail.com> (raw)
In-Reply-To: <CALCETrVXTXzXAmUsmmWxwr6vK+Vux7_pUzWPYyHjxEbn3ObABg@mail.gmail.com>

On Thu, Aug 8, 2013 at 12:25 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>
> Whoops -- I read your email too quickly.  I haven't tried
> MADV_WILLNEED, but I think I tried reading each page to fault them in.
>  Is there any reason to expect MADV_WILLNEED to do any better?  I'll
> try to do some new tests to see how well this all works.
>
> (I imagine that freshly fallocated files are somehow different when
> read, since there aren't zeros on the disk backing them until they get
> written.)

Well, this will teach me to write code based on an old benchmark from
memory.  It seems that prefaulting for read is okay on Linux 3.9 --
latencytop isn't do_wp_page or ext4* at all, at least not for the last
couple minutes on my test box.

I wonder if ext4 changed its handling of fallocated extents somewhere
between 3.5 and 3.9.  In any case, please consider these patches
withdrawn for the time being.

* With file_update_time stubbed out.  I need to dust off my old
patches to fix that part.

--
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  parent reply	other threads:[~2013-08-09  0:11 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-05 19:43 [RFC 0/3] Add madvise(..., MADV_WILLWRITE) Andy Lutomirski
2013-08-05 19:43 ` Andy Lutomirski
2013-08-05 19:43 ` [RFC 1/3] mm: Add MADV_WILLWRITE to indicate that a range will be written to Andy Lutomirski
2013-08-05 19:43   ` Andy Lutomirski
2013-08-05 19:44 ` [RFC 2/3] fs: Add block_willwrite Andy Lutomirski
2013-08-05 19:44   ` Andy Lutomirski
2013-08-05 19:44 ` [RFC 3/3] ext4: Implement willwrite for the delalloc case Andy Lutomirski
2013-08-05 19:44   ` Andy Lutomirski
2013-08-07 13:40 ` [RFC 0/3] Add madvise(..., MADV_WILLWRITE) Jan Kara
2013-08-07 13:40   ` Jan Kara
2013-08-07 17:02   ` Andy Lutomirski
2013-08-07 17:02     ` Andy Lutomirski
2013-08-07 17:40   ` Dave Hansen
2013-08-07 17:40     ` Dave Hansen
2013-08-07 18:00     ` Andy Lutomirski
2013-08-07 18:00       ` Andy Lutomirski
2013-08-08 10:18       ` Jan Kara
2013-08-08 10:18         ` Jan Kara
2013-08-08 15:56         ` Andy Lutomirski
2013-08-08 15:56           ` Andy Lutomirski
2013-08-08 18:53           ` Jan Kara
2013-08-08 18:53             ` Jan Kara
2013-08-08 19:25             ` Andy Lutomirski
2013-08-08 19:25               ` Andy Lutomirski
2013-08-08 22:58               ` Dave Hansen
2013-08-08 22:58                 ` Dave Hansen
2013-08-09  7:55                 ` Jan Kara
2013-08-09  7:55                   ` Jan Kara
2013-08-09 17:36                   ` Andy Lutomirski
2013-08-09 17:36                     ` Andy Lutomirski
2013-08-09 20:34                     ` Jan Kara
2013-08-09 20:34                       ` Jan Kara
2013-08-09 17:42                   ` Dave Hansen
2013-08-09 17:42                     ` Dave Hansen
2013-08-09 17:44                     ` Andy Lutomirski
2013-08-09 17:44                       ` Andy Lutomirski
2013-08-12 22:44                   ` Dave Hansen
2013-08-12 22:44                     ` Dave Hansen
2013-08-09  0:11               ` Andy Lutomirski [this message]
2013-08-09  0:11                 ` Andy Lutomirski

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