linux-kernel - Re: [PATCH for-next v3 0/3] implement pcpu bio caching for IRQ I/O

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Date:   Tue, 25 Oct 2022 15:51:52 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Kanchan Joshi <joshi.k@...sung.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH for-next v3 0/3] implement pcpu bio caching for IRQ I/O

On 10/25/22 14:25, Kanchan Joshi wrote:
> On Fri, Oct 21, 2022 at 11:34:04AM +0100, Pavel Begunkov wrote:
>> Add bio pcpu caching for normal / IRQ-driven I/O extending REQ_ALLOC_CACHE,
>> which was limited to iopoll. 
> 
> So below comment (stating process context as MUST) can also be removed as
> part of this series now?

Right, good point


> 495  * If REQ_ALLOC_CACHE is set, the final put of the bio MUST be done from process
> 496  * context, not hard/soft IRQ.
> 497  *
> 498  * Returns: Pointer to new bio on success, NULL on failure.
> 499  */
> 500 struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
> 501                              blk_opf_t opf, gfp_t gfp_mask,
> 502                              struct bio_set *bs)
> 503 {
[...]
>> The next step will be turning it on for other users, hopefully by default.
>> The only restriction we currently have is that the allocations can't be
>> done from non-irq context and so needs auditing.
> 
> Isn't allocation (of bio) happening in non-irq context already?

That's my assumption, true for most of them, but I need to actually
check that. Will be following up after this series is merged.


> Reviewed-by: Kanchan Joshi <joshi.k@...sung.com>

thanks

-- 
Pavel Begunkov