From: Christoph Hellwig <[email protected]>
To: Jens Axboe <[email protected]>
Cc: "[email protected]" <[email protected]>,
io-uring <[email protected]>,
Christoph Hellwig <[email protected]>
Subject: Re: [PATCH RFC] Enable bio cache for IRQ driven IO from io_uring
Date: Thu, 19 Aug 2021 11:01:50 +0200 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On Wed, Aug 18, 2021 at 10:54:45AM -0600, Jens Axboe wrote:
> We previously enabled this for O_DIRECT polled IO, however io_uring
> completes all IO from task context these days, so it can be enabled for
> that path too. This requires moving the bio_put() from IRQ context, and
> this can be accomplished by passing the ownership back to the issuer.
>
> Use kiocb->private for that, which should be (as far as I can tell) free
> once we get to the completion side of things. Add a IOCB_PUT_CACHE flag
> to tell the issuer that we passed back the ownership, then the issuer
> can put the bio from a safe context.
>
> Like the polled IO ditto, this is good for a 10% performance increase.
>
> Signed-off-by: Jens Axboe <[email protected]>
>
> ---
>
> Just hacked this up and tested it, Works For Me. Would welcome input on
> alternative methods here, if anyone has good suggestions.
10% performance improvement looks really nice, but I don't think we can
just hardcode assumptions about bios in iomap->private. The easiest
would be to call back into the file systems for the freeing, but that
would add an indirect call.
next prev parent reply other threads:[~2021-08-19 9:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 16:54 [PATCH RFC] Enable bio cache for IRQ driven IO from io_uring Jens Axboe
2021-08-19 9:01 ` Christoph Hellwig [this message]
2021-08-19 15:15 ` Jens Axboe
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