From: Paolo <paolo.valente@linaro.org>
To: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>,
Fabio Checconi <fchecconi@gmail.com>,
Arianna Avanzini <avanzini.arianna@gmail.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org
Subject: Re: [PATCH RFC 10/22] block, bfq: add full hierarchical scheduling and cgroups support
Date: Wed, 20 Apr 2016 11:32:23 +0200 [thread overview]
Message-ID: <57174CA7.5000706@linaro.org> (raw)
In-Reply-To: <20160211222824.GD3741@mtj.duckdns.org>
[Resending in plain text]
Il 11/02/2016 23:28, Tejun Heo ha scritto:
> Hello, > > On Mon, Feb 01, 2016 at 11:12:46PM +0100, Paolo Valente wrote: >>
From: Arianna Avanzini <avanzini.arianna@gmail.com> >> >> Complete
support for full hierarchical scheduling, with a cgroups >> interface.
The name of the added policy is bfq. >> >> Weights can be assigned
explicitly to groups and processes through the >> cgroups interface,
differently from what happens, for single >> processes, if the cgroups
interface is not used (as explained in the >> description of the
previous patch). In particular, since each node has >> a full scheduler,
each group can be assigned its own weight. > > * It'd be great if how
cgroup support is achieved is better > documented. > > * How's
writeback handled? > > * After all patches are applied, both
CONFIG_BFQ_GROUP_IOSCHED and > CONFIG_CFQ_GROUP_IOSCHED exist. > > *
The default weight and weight range don't seem to follow the defined >
interface on the v2 hierarchy. The default value should be 100. > > *
With all patches applied, booting triggers a RCU context warning. >
Please build with lockdep and RCU debugging turned on and fix the >
issue. > > * I was testing on the v2 hierarchy with two top-level
cgroups one > hosting sequential workload and the other completely
random. While > they eventually converged to a reasonable state,
starting up the > sequential workload while the random workload was
running was > extremely slow. It crawled for quite a while.
This malfunction seems related to a blkcg behavior that I did not
expect: the sequential writer changes group continuously. It moves
from the root group to its correct group, and back. Here is the
output of
egrep 'insert_request|changed cgroup' trace
over a trace taken with the original version of cfq (seq_write is of
course the group of the writer):
kworker/u8:2-96 [000] d... 204.561086: 8,0 m N cfq96A
/seq_write changed cgroup
kworker/u8:2-96 [000] d... 204.561097: 8,0 m N cfq96A
/ changed cgroup
kworker/u8:2-96 [000] d... 204.561353: 8,0 m N cfq96A
/ insert_request
kworker/u8:2-96 [000] d... 204.561369: 8,0 m N cfq96A
/seq_write insert_request
kworker/u8:2-96 [000] d... 204.561379: 8,0 m N cfq96A
/seq_write insert_request
kworker/u8:2-96 [000] d... 204.566509: 8,0 m N cfq96A
/seq_write changed cgroup
kworker/u8:2-96 [000] d... 204.566517: 8,0 m N cfq96A
/ changed cgroup
kworker/u8:2-96 [000] d... 204.566690: 8,0 m N cfq96A
/ insert_request
kworker/u8:2-96 [000] d... 204.567203: 8,0 m N cfq96A
/seq_write insert_request
kworker/u8:2-96 [000] d... 204.567216: 8,0 m N cfq96A
/seq_write insert_request
kworker/u8:2-96 [000] d... 204.567328: 8,0 m N cfq96A
/seq_write insert_request
kworker/u8:2-96 [000] d... 204.571622: 8,0 m N cfq96A
/seq_write changed cgroup
kworker/u8:2-96 [000] d... 204.571640: 8,0 m N cfq96A
/ changed cgroup
kworker/u8:2-96 [000] d... 204.572021: 8,0 m N cfq96A
/ insert_request
kworker/u8:2-96 [000] d... 204.572463: 8,0 m N cfq96A
/seq_write insert_request
...
For reasons that I don't yet know, group changes are much more
frequent with bfq, which ultimately causes bfq to fail to isolate the
writer from the reader.
While I go on trying to understand why, could you please tell me
whether this fluctuation is normal, and/or point me to documentation from
which I can better understand this behavior, without bothering you
further?
Thanks,
Paolo
> > * And "echo 100 > io.weight" hung the writing process. > > Thanks. >
next prev parent reply other threads:[~2016-04-20 9:32 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-01 22:12 [PATCH RFC 00/22] Replace the CFQ I/O Scheduler with BFQ Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 01/22] block, cfq: remove queue merging for close cooperators Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 02/22] block, cfq: remove close-based preemption Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 03/22] block, cfq: remove deep seek queues logic Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 04/22] block, cfq: remove SSD-related logic Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 05/22] block, cfq: get rid of hierarchical support Paolo Valente
2016-02-10 23:04 ` Tejun Heo
2016-02-01 22:12 ` [PATCH RFC 06/22] block, cfq: get rid of queue preemption Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 07/22] block, cfq: get rid of workload type Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 08/22] block, cfq: get rid of latency tunables Paolo Valente
2016-02-10 23:05 ` Tejun Heo
2016-02-01 22:12 ` [PATCH RFC 09/22] block, cfq: replace CFQ with the BFQ-v0 I/O scheduler Paolo Valente
2016-02-11 22:22 ` Tejun Heo
2016-02-12 0:35 ` Mark Brown
2016-02-17 15:57 ` Tejun Heo
2016-02-17 16:02 ` Mark Brown
2016-02-17 17:04 ` Tejun Heo
2016-02-17 18:13 ` Jonathan Corbet
2016-02-17 19:45 ` Tejun Heo
2016-02-17 19:56 ` Jonathan Corbet
2016-02-17 20:14 ` Tejun Heo
2016-02-17 9:02 ` Paolo Valente
2016-02-17 17:02 ` Tejun Heo
2016-02-20 10:23 ` Paolo Valente
2016-02-20 11:02 ` Paolo Valente
2016-03-01 18:46 ` Tejun Heo
2016-03-04 17:29 ` Linus Walleij
2016-03-04 17:39 ` Christoph Hellwig
2016-03-04 18:10 ` Austin S. Hemmelgarn
2016-03-11 11:16 ` Christoph Hellwig
2016-03-11 13:38 ` Austin S. Hemmelgarn
2016-03-05 12:18 ` Linus Walleij
2016-03-11 11:17 ` Christoph Hellwig
2016-03-11 11:24 ` Nikolay Borisov
2016-03-11 11:49 ` Christoph Hellwig
2016-03-11 14:53 ` Linus Walleij
2016-03-09 6:55 ` Paolo Valente
2016-04-13 19:54 ` Tejun Heo
2016-04-14 5:03 ` Mark Brown
2016-03-09 6:34 ` Paolo Valente
2016-04-13 20:41 ` Tejun Heo
2016-04-14 10:23 ` Paolo Valente
2016-04-14 16:29 ` Tejun Heo
2016-04-15 14:20 ` Paolo Valente
2016-04-15 15:08 ` Tejun Heo
2016-04-15 16:17 ` Paolo Valente
2016-04-15 19:29 ` Tejun Heo
2016-04-15 22:08 ` Paolo Valente
2016-04-15 22:45 ` Tejun Heo
2016-04-16 6:03 ` Paolo Valente
2016-04-15 14:49 ` Linus Walleij
2016-02-01 22:12 ` [PATCH RFC 10/22] block, bfq: add full hierarchical scheduling and cgroups support Paolo Valente
2016-02-11 22:28 ` Tejun Heo
2016-02-17 9:07 ` Paolo Valente
2016-02-17 17:14 ` Tejun Heo
2016-02-17 17:45 ` Tejun Heo
2016-04-20 9:32 ` Paolo [this message]
2016-04-22 18:13 ` Tejun Heo
2016-04-22 18:19 ` Paolo Valente
2016-04-22 18:41 ` Tejun Heo
2016-04-22 19:05 ` Paolo Valente
2016-04-22 19:32 ` Tejun Heo
2016-04-23 7:07 ` Paolo Valente
2016-04-25 19:24 ` Tejun Heo
2016-04-25 20:30 ` Paolo
2016-05-06 20:20 ` Paolo Valente
2016-05-12 13:11 ` Paolo
2016-07-27 16:13 ` [PATCH RFC V8 00/22] Replace the CFQ I/O Scheduler with BFQ Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 01/22] block, cfq: remove queue merging for close cooperators Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 02/22] block, cfq: remove close-based preemption Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 03/22] block, cfq: remove deep seek queues logic Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 04/22] block, cfq: remove SSD-related logic Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 05/22] block, cfq: get rid of hierarchical support Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 06/22] block, cfq: get rid of queue preemption Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 07/22] block, cfq: get rid of workload type Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 08/22] block, cfq: get rid of latency tunables Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 09/22] block, cfq: replace CFQ with the BFQ-v0 I/O scheduler Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 10/22] block, bfq: add full hierarchical scheduling and cgroups support Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 11/22] block, bfq: improve throughput boosting Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 12/22] block, bfq: modify the peak-rate estimator Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 13/22] block, bfq: add more fairness with writes and slow processes Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 14/22] block, bfq: improve responsiveness Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 15/22] block, bfq: reduce I/O latency for soft real-time applications Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 16/22] block, bfq: preserve a low latency also with NCQ-capable drives Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 17/22] block, bfq: reduce latency during request-pool saturation Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 18/22] block, bfq: add Early Queue Merge (EQM) Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 19/22] block, bfq: reduce idling only in symmetric scenarios Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 20/22] block, bfq: boost the throughput on NCQ-capable flash-based devices Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 21/22] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs Paolo Valente
2016-07-27 16:13 ` [PATCH RFC V8 22/22] block, bfq: handle bursts of queue activations Paolo Valente
2016-07-28 16:50 ` [PATCH RFC V8 00/22] Replace the CFQ I/O Scheduler with BFQ Paolo
2016-02-01 22:12 ` [PATCH RFC 11/22] block, bfq: improve throughput boosting Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 12/22] block, bfq: modify the peak-rate estimator Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 13/22] block, bfq: add more fairness to boost throughput and reduce latency Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 14/22] block, bfq: improve responsiveness Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 15/22] block, bfq: reduce I/O latency for soft real-time applications Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 16/22] block, bfq: preserve a low latency also with NCQ-capable drives Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 17/22] block, bfq: reduce latency during request-pool saturation Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 18/22] block, bfq: add Early Queue Merge (EQM) Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 19/22] block, bfq: reduce idling only in symmetric scenarios Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 20/22] block, bfq: boost the throughput on NCQ-capable flash-based devices Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 21/22] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs Paolo Valente
2016-02-01 22:12 ` [PATCH RFC 22/22] block, bfq: handle bursts of queue activations Paolo Valente
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