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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
	axboe@fb.com, Matias Bjorling <mb@lightnvm.io>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 01/10] block: don't decrement nr_phys_segments for physically contigous segments
Date: Tue, 14 May 2019 15:51:42 +0200	[thread overview]
Message-ID: <20190514135141.GA13683@lst.de> (raw)
In-Reply-To: <20190514090544.GC20468@ming.t460p>

On Tue, May 14, 2019 at 05:05:45PM +0800, Ming Lei wrote:
> However we still may make it better, for example, the attached patch can
> save 10~20% time when running 'mkfs.ntfs -s 512 /dev/vda', lots of small
> request(63KB) can be merged to big IO(1MB).

And we could save even more time by making the block dev buffered I/O
path not do stupid things to start with.

> > With the gap devices we have unlimited segment size, see my next patch
> > to actually enforce that.  Which is much more efficient than using
> 
> But this patch does effect on non-gap device, and actually most of
> device are non-gap type.

Yes, but only for request merges, and only if merging the requests
goes over max_requests.  The upside is that we actually get a
nr_phys_segments that mirrors what is in the request, fixing bugs
in a few drivers, and allowing for follow on patches that significantly
simplify our I/O path.

  reply	other threads:[~2019-05-14 13:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13  6:37 fix nr_phys_segments vs iterators accounting Christoph Hellwig
2019-05-13  6:37 ` [PATCH 01/10] block: don't decrement nr_phys_segments for physically contigous segments Christoph Hellwig
2019-05-13  9:45   ` Ming Lei
2019-05-13 12:03     ` Christoph Hellwig
2019-05-13 12:37       ` Christoph Hellwig
2019-05-14  4:36       ` Ming Lei
2019-05-14  5:14         ` Christoph Hellwig
2019-05-14  9:05           ` Ming Lei
2019-05-14 13:51             ` Christoph Hellwig [this message]
2019-05-14 13:57               ` Hannes Reinecke
2019-05-14 14:27               ` Ming Lei
2019-05-14 14:31                 ` Christoph Hellwig
2019-05-14 14:32                   ` Christoph Hellwig
2019-05-13  6:37 ` [PATCH 02/10] block: force an unlimited segment size on queues with a virt boundary Christoph Hellwig
2019-05-15  8:19   ` Ming Lei
2019-05-13  6:37 ` [PATCH 03/10] block: remove the segment size check in bio_will_gap Christoph Hellwig
2019-05-15  8:34   ` Ming Lei
2019-05-13  6:37 ` [PATCH 04/10] block: remove the bi_seg_{front,back}_size fields in struct bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 05/10] block: initialize the write priority in blk_rq_bio_prep Christoph Hellwig
2019-05-13 15:04   ` Chaitanya Kulkarni
2019-05-13  6:37 ` [PATCH 06/10] block: remove blk_init_request_from_bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 07/10] block: remove the bi_phys_segments field in struct bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 08/10] block: simplify blk_recalc_rq_segments Christoph Hellwig
2019-05-13  6:37 ` [PATCH 09/10] block: untangle the end of blk_bio_segment_split Christoph Hellwig
2019-05-13  6:37 ` [PATCH 10/10] block: mark blk_rq_bio_prep as inline Christoph Hellwig
2019-05-13 14:57   ` Chaitanya Kulkarni
     [not found] ` <CGME20190513063855epcas5p33ef8c4c0a0055bd0b66eadc859796f0f@epcms2p6>
2019-05-13  7:34   ` [PATCH 05/10] block: initialize the write priority in blk_rq_bio_prep Minwoo Im

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