linux-kernel - Re: [PATCH 0/5] v2: block subsystem refcounter conversions

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Message-ID: <99e3518a-bb1a-cab2-80b8-dd466827b5e6@kernel.dk>
Date:   Fri, 21 Apr 2017 10:29:45 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Reshetova, Elena" <elena.reshetova@...el.com>,
        Eric Biggers <ebiggers3@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Christoph Hellwig <hch@...radead.org>,
        "james.bottomley@...senpartnership.com" 
        <james.bottomley@...senpartnership.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "fujita.tomonori@....ntt.co.jp" <fujita.tomonori@....ntt.co.jp>,
        "mingo@...hat.com" <mingo@...hat.com>, "clm@...com" <clm@...com>,
        "jbacik@...com" <jbacik@...com>,
        "dsterba@...e.com" <dsterba@...e.com>
Subject: Re: [PATCH 0/5] v2: block subsystem refcounter conversions

On 04/21/2017 09:22 AM, Peter Zijlstra wrote:
> On Fri, Apr 21, 2017 at 08:03:13AM -0600, Jens Axboe wrote:
>> You have it so easy - the code is completely standalone, building a
>> small test framework around it and measuring performance in _user space_
>> is trivial.
> 
> Something like this you mean:
> 
>   https://lkml.kernel.org/r/20170322165144.dtidvvbxey7w5pbd@hirez.programming.kicks-ass.net

Yes, exactly. But it'd be great to see better coverage of the API, and
various cases of X threads running operations on the same refcount,
so we get a full view of that side too. The above looks like just
counting cycles for a single op of foo_inc().

-- 
Jens Axboe