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
next prev parent 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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