linux-kernel - Re: [PATCH BUGFIX/IMPROVEMENT 0/2] block, bfq: two pending patches

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Message-Id: <8EB4BACE-3D6D-4EB7-844E-45092AC7644B@linaro.org>
Date:   Thu, 18 Jan 2018 09:25:43 +0100
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block <linux-block@...r.kernel.org>,
        linux-kernel@...r.kernel.org, ulf.hansson@...aro.org,
        broonie@...nel.org, linus.walleij@...aro.org,
        bfq-iosched@...glegroups.com, oleksandr@...alenko.name
Subject: Re: [PATCH BUGFIX/IMPROVEMENT 0/2] block, bfq: two pending patches



> Il giorno 13 gen 2018, alle ore 12:05, Paolo Valente <paolo.valente@...aro.org> ha scritto:
> 
> Hi Jens,
> here are again the two pending patches you asked me to resend [1]. One
> of them, fixing read-starvation problems, was accompanied by a cover
> letter. I'm pasting the content of that cover letter below.
> 
> The patch addresses (serious) starvation problems caused by
> request-tag exhaustion, as explained in more detail in the commit
> message. I started from the solution in the function
> kyber_limit_depth, but then I had to define more articulate limits, to
> counter starvation also in cases not covered in kyber_limit_depth.
> If this solution proves to be effective, I'm willing to port it
> somehow to the other schedulers.
> 

Hi Jens,
have had to time to check these patches?  Sorry for pushing, but I
guess 4.16 is getting closer, and these patches are performance
critical; especially the first, which solves a starvation problem.

Thanks,
Paolo

> Thanks,
> Paolo
> 
> [1] https://www.spinics.net/lists/linux-block/msg21586.html
> 
> Paolo Valente (2):
>  block, bfq: limit tags for writes and async I/O
>  block, bfq: limit sectors served with interactive weight raising
> 
> block/bfq-iosched.c | 158 +++++++++++++++++++++++++++++++++++++++++++++++++---
> block/bfq-iosched.h |  17 ++++++
> block/bfq-wf2q.c    |   3 +
> 3 files changed, 169 insertions(+), 9 deletions(-)
> 
> --
> 2.15.1