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From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: 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 22:27:17 +0800	[thread overview]
Message-ID: <20190514142716.GB25519@ming.t460p> (raw)
In-Reply-To: <20190514135141.GA13683@lst.de>

On Tue, May 14, 2019 at 03:51:42PM +0200, Christoph Hellwig wrote:
> 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.

I am wondering if it can be done easily, given mkfs is userspace
which only calls write syscall on block device. Or could you share
something about how to fix the stupid things?

> 
> > > 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.

non-gap device still has max segment size limit, and I guess it still
needs to be respected.


Thanks,
Ming

  parent reply	other threads:[~2019-05-14 14:27 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
2019-05-14 13:57               ` Hannes Reinecke
2019-05-14 14:27               ` Ming Lei [this message]
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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