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From: Eric Sandeen <sandeen@redhat.com>
To: Mark Lord <kernel@teksavvy.com>
Cc: Greg Freemyer <greg.freemyer@gmail.com>,
	Lukas Czerner <lczerner@redhat.com>,
	linux-ext4@vger.kernel.org, Jeff Moyer <jmoyer@redhat.com>,
	Edward Shishkin <eshishki@redhat.com>,
	Eric Sandeen <esandeen@redhat.com>,
	Ric Wheeler <rwheeler@redhat.com>
Subject: Re: [PATCH 2/2] Add batched discard support for ext4.
Date: Tue, 20 Apr 2010 21:45:25 -0500	[thread overview]
Message-ID: <4BCE66C5.3060906@redhat.com> (raw)
In-Reply-To: <4BCE6243.5010209@teksavvy.com>

Mark Lord wrote:
> On 20/04/10 05:21 PM, Greg Freemyer wrote:
>> Mark,
>>
>> This is the patch implementing the new discard logic.
> ..
>> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> ..
>>> +void ext4_trim_extent(struct super_block *sb, int start, int count,
>>> +               ext4_group_t group, struct ext4_buddy *e4b)
>>> +{
>>> +       ext4_fsblk_t discard_block;
>>> +       struct ext4_super_block *es = EXT4_SB(sb)->s_es;
>>> +       struct ext4_free_extent ex;
>>> +
>>> +       assert_spin_locked(ext4_group_lock_ptr(sb, group));
>>> +
>>> +       ex.fe_start = start;
>>> +       ex.fe_group = group;
>>> +       ex.fe_len = count;
>>> +
>>> +       mb_mark_used(e4b,&ex);
>>> +       ext4_unlock_group(sb, group);
>>> +
>>> +       discard_block = (ext4_fsblk_t)group *
>>> +                       EXT4_BLOCKS_PER_GROUP(sb)
>>> +                       + start
>>> +                       + le32_to_cpu(es->s_first_data_block);
>>> +       trace_ext4_discard_blocks(sb,
>>> +                       (unsigned long long)discard_block,
>>> +                       count);
>>> +       sb_issue_discard(sb, discard_block, count);
>>> +
>>> +       ext4_lock_group(sb, group);
>>> +       mb_free_blocks(NULL, e4b, start, ex.fe_len);
>>> +}
>>
>> Mark, unless I'm missing something, sb_issue_discard() above is going
>> to trigger a trim command for just the one range.  I thought the
>> benchmarks you did showed that a collection of ranges needed to be
>> built, then a single trim command invoked that trimmed that group of
>> ranges.
> ..
> 
> Mmm.. If that's what it is doing, then this patch set would be a
> complete disaster.
> It would take *hours* to do the initial TRIM.
> 
> Lukas ?

I'm confused; do we have an interface to send a trim command for multiple ranges?

I didn't think so ...  Lukas' patch is finding free ranges (above a size threshold)
to discard; it's not doing it a block at a time, if that's the concern.

-Eric

  reply	other threads:[~2010-04-21  2:45 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-19 10:55 Ext4: batched discard support Lukas Czerner
2010-04-19 10:55 ` [PATCH 1/2] Add ioctl FITRIM Lukas Czerner
2010-04-19 10:55   ` [PATCH 2/2] Add batched discard support for ext4 Lukas Czerner
2010-04-20 21:21     ` Greg Freemyer
2010-04-21  2:26       ` Mark Lord
2010-04-21  2:45         ` Eric Sandeen [this message]
2010-04-21 18:59           ` Greg Freemyer
2010-04-21 19:04             ` Ric Wheeler
2010-04-21 19:22               ` Jeff Moyer
2010-04-21 20:44                 ` Greg Freemyer
2010-04-21 20:53                   ` Greg Freemyer
2010-04-21 21:01                   ` Eric Sandeen
2010-04-21 21:03                     ` Ric Wheeler
2010-04-21 21:47                       ` Greg Freemyer
2010-04-21 21:56                         ` James Bottomley
2010-04-21 21:59                         ` Mark Lord
2010-04-23  8:23                   ` Lukas Czerner
2010-04-24 13:24                     ` Greg Freemyer
2010-04-24 13:48                       ` Ric Wheeler
2010-04-24 14:30                         ` Greg Freemyer
2010-04-24 14:43                           ` Eric Sandeen
2010-04-24 15:03                             ` Greg Freemyer
2010-04-24 17:04                               ` Ric Wheeler
2010-04-24 18:30                                 ` Greg Freemyer
2010-04-24 18:41                                   ` Ric Wheeler
2010-04-26 14:00                                     ` Mark Lord
2010-04-26 14:42                                       ` Martin K. Petersen
2010-04-26 15:27                                         ` Greg Freemyer
2010-04-26 15:51                                           ` Lukas Czerner
2010-04-28  1:25                                           ` Mark Lord
2010-04-26 15:48                                         ` Ric Wheeler
2010-04-24 19:06                                   ` Martin K. Petersen
2010-04-26 14:03                                     ` Mark Lord
2010-04-24 18:39                       ` Martin K. Petersen
2010-04-26 16:55                     ` Jan Kara
2010-04-26 17:46                       ` Lukas Czerner
2010-04-26 17:52                         ` Ric Wheeler
2010-04-26 18:14                           ` Lukas Czerner
2010-04-26 18:28                             ` Jeff Moyer
2010-04-26 18:38                               ` [PATCH 2/2] Add batched discard support for ext4 - using rbtree Lukas Czerner
2010-04-26 18:42                                 ` Lukas Czerner
2010-04-27 15:29                                   ` Edward Shishkin
2010-04-21 20:52                 ` [PATCH 2/2] Add batched discard support for ext4 Greg Freemyer
2010-04-19 16:20 ` Ext4: batched discard support Greg Freemyer
2010-04-19 16:30   ` Eric Sandeen
2010-04-19 17:58     ` Greg Freemyer
2010-04-19 18:04       ` Ric Wheeler
2010-04-20 20:24   ` Mark Lord
2010-04-20 20:34     ` Mark Lord
  -- strict thread matches above, loose matches on Subject: below --
2010-07-07  7:53 Ext4: batched discard support - simplified version Lukas Czerner
2010-07-07  7:53 ` [PATCH 2/2] Add batched discard support for ext4 Lukas Czerner
2010-07-14  8:33   ` Dmitry Monakhov
2010-07-14  9:40     ` Lukas Czerner
2010-07-14 10:03       ` Dmitry Monakhov
2010-07-14 11:43         ` Lukas Czerner

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