linux-kernel - Re: [PATCH 0/6] v4 block refcount conversion patches

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Message-ID: <mqdr2typ5uw.fsf@linux-x5ow.site>
Date:   Fri, 20 Oct 2017 10:43:03 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Elena Reshetova <elena.reshetova@...el.com>
Cc:     axboe@...nel.dk, james.bottomley@...senpartnership.com,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-btrfs@...r.kernel.org,
        peterz@...radead.org, gregkh@...uxfoundation.org,
        fujita.tomonori@....ntt.co.jp, mingo@...hat.com, clm@...com,
        jbacik@...com, dsterba@...e.com, keescook@...omium.org
Subject: Re: [PATCH 0/6] v4 block refcount conversion patches

Elena Reshetova <elena.reshetova@...el.com> writes:
> Elena Reshetova (6):
>   block: convert bio.__bi_cnt from atomic_t to refcount_t
>   block: convert blk_queue_tag.refcnt from atomic_t to refcount_t
>   block: convert blkcg_gq.refcnt from atomic_t to refcount_t
>   block: convert io_context.active_ref from atomic_t to refcount_t
>   block: convert bsg_device.ref_count from atomic_t to refcount_t
>   drivers, block: convert xen_blkif.refcnt from atomic_t to refcount_t

Hi Elena,

While the bsg ref_count is cheap, do you have any numbers how the other
conversions compare in performance (throughput and latency) vs atomics?

It should be quite easy to measure against a null_blk device.

Thanks a lot,
       Johannes

-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
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