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[146.241.25.197]) by smtp.gmail.com with ESMTPSA id i47sm6387297wra.97.2017.12.27.04.15.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Dec 2017 04:15:19 -0800 (PST) From: Paolo Valente To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, linus.walleij@linaro.org, bfq-iosched@googlegroups.com, Paolo Valente Subject: [PATCH IMPROVEMENT/BUGFIX 0/1] block, bfq: address starvation caused by tag consumption Date: Wed, 27 Dec 2017 13:15:06 +0100 Message-Id: <20171227121507.4280-1-paolo.valente@linaro.org> X-Mailer: git-send-email 2.15.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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