linux-kernel - Re: [PATCH] block: switch to atomic

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Message-ID: <282666e2-93d4-0302-b2d0-47d03395a6d4@kernel.dk>
Date:   Mon, 6 Dec 2021 11:13:20 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] block: switch to atomic_t for request references

On 12/6/21 10:35 AM, Linus Torvalds wrote:
> On Mon, Dec 6, 2021 at 12:31 AM Peter Zijlstra <peterz@...radead.org> wrote:
>>
>> Quite; and for something that pretends to be about performance, it also
>> lacks any actual numbers to back that claim.
>>
>> The proposed implementation also doesn't do nearly as much as the
>> refcount_t one does.
> 
> Stop pretending refcoutn_t is that great.
> 
> It's horrid. The code it generators is disgusting. It should never
> have been inlines in the first place, and the design decsisions were
> questionable to begin with.
> 
> There's a reason core stuff (like the page counters) DO NOT USE REFCOUNT_T.
> 
> I seriously believe that refcount_t should be used for things like
> device reference counting or similar issues, and not for _any_ truly
> core code.

Maybe we just need to embrace it generically, took a quick stab at it
which is attached. Totally untested...

-- 
Jens Axboe


View attachment "0004-mm-convert-to-using-atomic-ref.patch" of type "text/x-patch" (1389 bytes)

View attachment "0003-block-convert-to-using-atomic-ref.patch" of type "text/x-patch" (5149 bytes)

View attachment "0002-io_uring-convert-to-using-atomic-ref.patch" of type "text/x-patch" (2142 bytes)

View attachment "0001-atomic-ref-add-basic-infrastructure-for-atomic-refs-.patch" of type "text/x-patch" (1540 bytes)