From: Christoph Hellwig <[email protected]>
To: Jens Axboe <[email protected]>
Cc: [email protected], [email protected]
Subject: Re: [PATCH 3/3] block: enable bio allocation cache for IRQ driven IO
Date: Thu, 16 Dec 2021 06:33:04 -0800 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On Wed, Dec 15, 2021 at 09:30:09AM -0700, Jens Axboe wrote:
> We currently cannot use the bio recycling allocation cache for IRQ driven
> IO, as the cache isn't IRQ safe (by design).
>
> Add a way for the completion side to pass back a bio that needs freeing,
> so we can do it from the io_uring side. io_uring completions always
> run in task context.
>
> This is good for about a 13% improvement in IRQ driven IO, taking us from
> around 6.3M/core to 7.1M/core IOPS.
The numbers looks great, but I really hate how it ties the caller into
using a bio. I'll have to think hard about a better structure.
Just curious: are the numbers with retpolines or without? Do you care
about the cost of indirect calls with retpolines for these benchmarks?
next prev parent reply other threads:[~2021-12-16 14:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-15 16:30 [PATCHSET 0/3] Improve IRQ driven performance Jens Axboe
2021-12-15 16:30 ` [PATCH 1/3] block: add completion handler for fast path Jens Axboe
2021-12-16 9:10 ` Christoph Hellwig
2021-12-15 16:30 ` [PATCH 2/3] block: use singly linked list for bio cache Jens Axboe
2021-12-16 9:11 ` Christoph Hellwig
2021-12-15 16:30 ` [PATCH 3/3] block: enable bio allocation cache for IRQ driven IO Jens Axboe
2021-12-16 14:33 ` Christoph Hellwig [this message]
2021-12-16 15:41 ` Jens Axboe
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