From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-s390@vger.kernel.org, linux-bcache@vger.kernel.org,
Coly Li <colyli@suse.de>,
linux-raid@vger.kernel.org, Song Liu <song@kernel.org>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
Tejun Heo <tj@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [dm-devel] [PATCH 3/9] block: store a block_device pointer in struct bio
Date: Thu, 3 Dec 2020 09:29:51 +0100 [thread overview]
Message-ID: <20201203082951.GA15581@lst.de> (raw)
In-Reply-To: <20201203071055.GA633702@T590>
On Thu, Dec 03, 2020 at 03:10:55PM +0800, Ming Lei wrote:
> On Thu, Dec 03, 2020 at 02:40:04PM +0800, Ming Lei wrote:
> > On Tue, Dec 01, 2020 at 05:54:18PM +0100, Christoph Hellwig wrote:
> > > Replace the gendisk pointer in struct bio with a pointer to the newly
> > > improved struct block device. From that the gendisk can be trivially
> > > accessed with an extra indirection, but it also allows to directly
> > > look up all information related to partition remapping.
> >
> > The extra indirection is often done in fast path, so just wondering why
> > you don't consider to embed gendisk into block_device? Then the extra
> > indirection can be avoided.
>
> oops, that is only possible for disk, and indirection is still needed
> for partitions.
I looked into that, but given that the block device is allocated as part
of the inode we'd need to tell ->alloc_inode if we want to allocate the
small inode without the gendisk, or the large one with it which doesn't
work with the current interface. Beause the hd_struct is gone we're
still not using more structures in the I/O path than we did before.
--
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dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Tejun Heo <tj@kernel.org>, Coly Li <colyli@suse.de>,
Song Liu <song@kernel.org>,
dm-devel@redhat.com, linux-bcache@vger.kernel.org,
linux-raid@vger.kernel.org, linux-s390@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: [PATCH 3/9] block: store a block_device pointer in struct bio
Date: Thu, 3 Dec 2020 09:29:51 +0100 [thread overview]
Message-ID: <20201203082951.GA15581@lst.de> (raw)
In-Reply-To: <20201203071055.GA633702@T590>
On Thu, Dec 03, 2020 at 03:10:55PM +0800, Ming Lei wrote:
> On Thu, Dec 03, 2020 at 02:40:04PM +0800, Ming Lei wrote:
> > On Tue, Dec 01, 2020 at 05:54:18PM +0100, Christoph Hellwig wrote:
> > > Replace the gendisk pointer in struct bio with a pointer to the newly
> > > improved struct block device. From that the gendisk can be trivially
> > > accessed with an extra indirection, but it also allows to directly
> > > look up all information related to partition remapping.
> >
> > The extra indirection is often done in fast path, so just wondering why
> > you don't consider to embed gendisk into block_device? Then the extra
> > indirection can be avoided.
>
> oops, that is only possible for disk, and indirection is still needed
> for partitions.
I looked into that, but given that the block device is allocated as part
of the inode we'd need to tell ->alloc_inode if we want to allocate the
small inode without the gendisk, or the large one with it which doesn't
work with the current interface. Beause the hd_struct is gone we're
still not using more structures in the I/O path than we did before.
next prev parent reply other threads:[~2020-12-03 8:31 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 16:54 [dm-devel] store a pointer to the block_device in struct bio (again) Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-01 16:54 ` [dm-devel] [PATCH 1/9] brd: remove the end of device check in brd_do_bvec Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 22:39 ` [dm-devel] " Tejun Heo
2020-12-02 22:39 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 2/9] dcssblk: " Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 22:39 ` [dm-devel] " Tejun Heo
2020-12-02 22:39 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 3/9] block: store a block_device pointer in struct bio Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 22:54 ` [dm-devel] " Tejun Heo
2020-12-02 22:54 ` Tejun Heo
2020-12-03 6:39 ` [dm-devel] " Ming Lei
2020-12-03 6:39 ` Ming Lei
2020-12-03 7:10 ` [dm-devel] " Ming Lei
2020-12-03 7:10 ` Ming Lei
2020-12-03 8:29 ` Christoph Hellwig [this message]
2020-12-03 8:29 ` Christoph Hellwig
2020-12-03 9:32 ` [dm-devel] " Ming Lei
2020-12-03 9:32 ` Ming Lei
2020-12-03 20:53 ` [dm-devel] " Keith Busch
2020-12-03 20:53 ` Keith Busch
2020-12-01 16:54 ` [dm-devel] [PATCH 4/9] block: simplify submit_bio_checks a bit Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 22:55 ` [dm-devel] " Tejun Heo
2020-12-02 22:55 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 5/9] block: use ->bi_bdev for bio based I/O accounting Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 23:05 ` [dm-devel] " Tejun Heo
2020-12-02 23:05 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 6/9] blk-mq: use ->bi_bdev for " Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 23:06 ` [dm-devel] " Tejun Heo
2020-12-02 23:06 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 7/9] block: add a disk_uevent helper Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 23:08 ` [dm-devel] " Tejun Heo
2020-12-02 23:08 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 8/9] block: remove DISK_PITER_REVERSE Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 23:15 ` [dm-devel] " Tejun Heo
2020-12-02 23:15 ` Tejun Heo
2020-12-01 16:54 ` [dm-devel] [PATCH 9/9] block: use an xarray for disk->part_tbl Christoph Hellwig
2020-12-01 16:54 ` Christoph Hellwig
2020-12-02 23:22 ` [dm-devel] " Tejun Heo
2020-12-02 23:22 ` Tejun Heo
2020-12-02 22:35 ` [dm-devel] store a pointer to the block_device in struct bio (again) Tejun Heo
2020-12-02 22:35 ` Tejun Heo
2020-12-02 22:37 ` [dm-devel] " Tejun Heo
2020-12-02 22:37 ` Tejun Heo
2020-12-04 16:43 ` [dm-devel] " Jens Axboe
2020-12-04 16:43 ` Jens Axboe
2020-12-07 18:56 ` [dm-devel] " Qian Cai
2020-12-07 18:56 ` Qian Cai
2020-12-07 19:01 ` [dm-devel] " Christoph Hellwig
2020-12-07 19:01 ` Christoph Hellwig
2020-12-07 20:20 ` [dm-devel] " Jens Axboe
2020-12-07 20:20 ` Jens Axboe
2020-12-08 11:04 ` [dm-devel] " Christoph Hellwig
2020-12-08 11:04 ` Christoph Hellwig
2020-12-08 13:08 ` [dm-devel] " Qian Cai
2020-12-08 13:08 ` Qian Cai
2020-12-08 13:38 ` [dm-devel] " Daniel Wagner
2020-12-08 13:38 ` Daniel Wagner
2020-12-08 14:15 ` [dm-devel] " Jens Axboe
2020-12-08 14:15 ` Jens Axboe
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