From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>,
Jeffle Xu <jefflexu@linux.alibaba.com>,
Ming Lei <ming.lei@redhat.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: switch block layer polling to a bio based model
Date: Mon, 26 Apr 2021 18:15:03 +0200 [thread overview]
Message-ID: <20210426161503.GA30994@lst.de> (raw)
In-Reply-To: <6b7e3ba0-aa09-b86d-8ea1-dc2e78c7529e@kernel.dk>
On Mon, Apr 26, 2021 at 09:12:09AM -0600, Jens Axboe wrote:
> Here's the series. It's not super clean (yet), but basically allows
> users like io_uring to setup a bio cache, and pass that in through
> iocb->ki_bi_cache. With that, we can recycle them instead of going
> through free+alloc continually. If you look at profiles for high iops,
> we're spending more time than desired doing just that.
>
> https://git.kernel.dk/cgit/linux-block/log/?h=io_uring-bio-cache
So where do you spend the cycles? The do not memset the whole bio
optimization is pretty obvious and is someting we should do independent
of the allocator.
The other thing that sucks is the mempool implementation, as it forces
each allocation and free to do an indirect call. I think it might be
worth to try to frontend it with a normal slab cache and only fall back
to the mempool if that fails.
next prev parent reply other threads:[~2021-04-26 16:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 13:48 switch block layer polling to a bio based model Christoph Hellwig
2021-04-26 13:48 ` [PATCH 01/12] direct-io: remove blk_poll support Christoph Hellwig
2021-04-26 13:48 ` [PATCH 02/12] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO Christoph Hellwig
2021-04-26 13:48 ` [PATCH 03/12] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw Christoph Hellwig
2021-04-26 13:48 ` [PATCH 04/12] blk-mq: factor out a "classic" poll helper Christoph Hellwig
2021-04-26 13:48 ` [PATCH 05/12] blk-mq: factor out a blk_qc_to_hctx helper Christoph Hellwig
2021-04-26 13:48 ` [PATCH 06/12] blk-mq: refactor hybrid polling Christoph Hellwig
2021-04-26 13:48 ` [PATCH 07/12] blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal Christoph Hellwig
2021-04-26 13:48 ` [PATCH 08/12] blk-mq: remove blk_qc_t_valid Christoph Hellwig
2021-04-26 13:48 ` [PATCH 09/12] block: rename REQ_HIPRI to REQ_POLLED Christoph Hellwig
2021-04-26 13:48 ` [PATCH 10/12] block: RCU free polled bios Christoph Hellwig
2021-04-26 13:48 ` [PATCH 11/12] block: define 'struct bvec_iter' as packed Christoph Hellwig
2021-04-26 13:48 ` [PATCH 12/12] block: switch polling to be bio based Christoph Hellwig
2021-04-26 15:27 ` Ming Lei
2021-04-26 14:57 ` switch block layer polling to a bio based model Jens Axboe
2021-04-26 15:06 ` Christoph Hellwig
2021-04-26 15:12 ` Jens Axboe
2021-04-26 16:15 ` Christoph Hellwig [this message]
2021-04-26 16:48 ` Jens Axboe
2021-04-26 17:05 ` Christoph Hellwig
2021-04-26 17:18 ` Jens Axboe
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