linux-kernel - [PATCH IMPROVEMENT/BUGFIX 0/1] block, bfq: address starvation caused by tag consumption

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Message-Id: <20171227121507.4280-1-paolo.valente@linaro.org>
Date:   Wed, 27 Dec 2017 13:15:06 +0100
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     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,
        Paolo Valente <paolo.valente@...aro.org>
Subject: [PATCH IMPROVEMENT/BUGFIX 0/1] block, bfq: address starvation caused by tag consumption

Hi Jens, all,
here's the patch I anticipated in my last email. It 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.

Thanks,
Paolo

Paolo Valente (1):
  block, bfq: limit tags for writes and async I/O

 block/bfq-iosched.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 block/bfq-iosched.h | 12 +++++++++
 2 files changed, 89 insertions(+)

--
2.15.1