From: Jens Axboe <axboe@kernel.dk>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org,
dm-devel@redhat.com
Subject: Re: [PATCH v10 4/8] block: Add bio_reset()
Date: Fri, 07 Sep 2012 16:06:45 -0600 [thread overview]
Message-ID: <504A6FF5.3090603@kernel.dk> (raw)
In-Reply-To: <504A6D57.1030607@kernel.dk>
On 2012-09-07 15:55, Jens Axboe wrote:
> On 2012-09-07 14:58, Kent Overstreet wrote:
>> On Thu, Sep 06, 2012 at 07:34:18PM -0600, Jens Axboe wrote:
>>> On 2012-09-06 16:34, Kent Overstreet wrote:
>>>> Reusing bios is something that's been highly frowned upon in the past,
>>>> but driver code keeps doing it anyways. If it's going to happen anyways,
>>>> we should provide a generic method.
>>>>
>>>> This'll help with getting rid of bi_destructor - drivers/block/pktcdvd.c
>>>> was open coding it, by doing a bio_init() and resetting bi_destructor.
>>>>
>>>> This required reordering struct bio, but the block layer is not yet
>>>> nearly fast enough for any cacheline effects to matter here.
>>>
>>> That's an odd and misplaced comment. Was just doing testing today at 5M
>>> IOPS, and even years back we've had cache effects for O_DIRECT in higher
>>> speed setups.
>>
>> Ah, I wasn't aware that you were pushing that many iops through the
>> block layer - most I've tested myself was around 1M. It wouldn't
>> surprise me if cache effects in struct bio mattered around 5M...
>
> 5M is nothing, just did 13.5M :-)
>
> But we can reshuffle for now. As mentioned, we're way overdue for a
> decent look at cache profiling in any case.
No ill effects seen so far, fwiw:
read : io=1735.8GB, bw=53690MB/s, iops=13745K, runt= 33104msec
--
Jens Axboe
next prev parent reply other threads:[~2012-09-07 22:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-06 22:34 [PATCH v10 0/8] Block cleanups Kent Overstreet
2012-09-06 22:34 ` [PATCH v10 1/8] block: Generalized bio pool freeing Kent Overstreet
2012-09-14 18:28 ` [dm-devel] " Alasdair G Kergon
2012-09-17 20:51 ` Kent Overstreet
2012-09-18 16:31 ` Alasdair G Kergon
2012-09-14 18:36 ` Alasdair G Kergon
2012-09-06 22:34 ` [PATCH v10 2/8] block: Ues bi_pool for bio_integrity_alloc() Kent Overstreet
2012-09-06 22:34 ` [PATCH v10 3/8] dm: Use bioset's front_pad for dm_rq_clone_bio_info Kent Overstreet
2012-09-06 22:34 ` [PATCH v10 4/8] block: Add bio_reset() Kent Overstreet
2012-09-07 1:34 ` Jens Axboe
2012-09-07 20:58 ` Kent Overstreet
2012-09-07 21:55 ` Jens Axboe
2012-09-07 22:06 ` Jens Axboe [this message]
2012-09-07 22:25 ` Kent Overstreet
2012-09-07 22:44 ` Jens Axboe
2012-09-07 23:14 ` [dm-devel] " Alasdair G Kergon
2012-09-07 23:25 ` Kent Overstreet
2012-09-06 22:34 ` [PATCH v10 5/8] pktcdvd: Switch to bio_kmalloc() Kent Overstreet
2012-09-06 22:35 ` [PATCH v10 6/8] block: Kill bi_destructor Kent Overstreet
2012-09-06 23:42 ` Tejun Heo
2012-09-06 22:35 ` [PATCH v10 7/8] block: Consolidate bio_alloc_bioset(), bio_kmalloc() Kent Overstreet
2012-09-06 23:45 ` Tejun Heo
2012-09-06 22:35 ` [PATCH v10 8/8] block: Add bio_clone_bioset(), bio_clone_kmalloc() Kent Overstreet
2012-09-06 23:46 ` Tejun Heo
2012-09-14 21:50 ` [dm-devel] " Alasdair G Kergon
2012-09-17 20:42 ` Kent Overstreet
2012-09-18 16:15 ` Alasdair G Kergon
2012-09-06 23:48 ` [PATCH v10 0/8] Block cleanups Tejun Heo
2012-09-07 1:37 ` Jens Axboe
2012-09-07 20:44 ` Kent Overstreet
2012-09-11 4:43 ` NeilBrown
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