Il giorno 5 mar 2019, alle ore 17:18, stan <upaitag(a)zoho.com>
ha scritto:
On Tue, 5 Mar 2019 14:07:15 +0000
Alan Jenkins <alan.christopher.jenkins(a)gmail.com> wrote:
> On 13/12/2018, Laura Abbott <labbott(a)redhat.com> wrote:
>>
>> Thanks for starting this discussion. Based on this thread and
>> other discussions, I'm going to see about enabling BFQ for
>> 4.21. Once 4.21-rc1 comes out (i.e. almost all configs should
>> be in) we can review the settings and see if anything needs
>> to be adjusted. If I get some time before then (i.e. before
>> I leave for holiday) I'll see if I can change the defaults.
>>
>> Laura
>
> Are there any more up-to-date details on this? Specifically I am
> wondering if there will be any separate package providing udev rules,
> that people should be aware of, if they want to provide testing of 5.0
> kernels for Fedora.
I've been using the 5.0 kernels locally compiled and optimized for my
hardware with bfq enabled. I don't have multi thread hardware. The
performance has been comparable to cfq, or slightly worse.
Subjective.
I started testing 5.0 today too, with incredibly bad performance, on
an old Intel Core i7-2760QM(a)2.40GHz. I found out the bottleneck to be
the CPU (about 7x slowdown). After reporting this issue to some Linaro
guys (in CC), I've been suggested a tiresome bisection w.r.t. 4.20
(4.20 which works with no issue). I hope someone will show up with
the cause of the problem, relieving me of this burden :)
At any rate, let me take this opportunity for updating you guys on
what happened in the last months.
First, server-side, I discovered that the techniques used to guarantee
I/O bandwidth to clients, containers and virtual machines easily
result in throughput losses of up to 90%! So I improved BFQ so as to
make it an alternative solution that brings this loss down to just
10%. Full details in this very recent (today :) ) short article:
http://ow.ly/vsrW50mBAGl
Second, PC-side, I've pushed new commits for the dev version of BFQ
(I'll submit these commits for the production version, probably
tomorrow; so they'll probably be all available from 5.2). These
commits provide the following, measurable performance boost:
- up to ~80% faster application start-up times in the presence of
background workloads
- ~150% throughput boost in one of the nastiest workloads for BFQ the
one generated by dbench. The throughput is finally on pr with any
other I/O scheduler, and most likely equal to the maximum possible
throughput reachable with this test
- elimination of the 18% loss of throughput occurring with only
random reads, w.r.t. to none as I/O scheduler; there is no loss any
more;
For any question, I'll be glad to answer, if I can,
Paolo
And there could be other software changes affecting this.
I've recently also started using the gcc kernel-stack plugin to clean
stack on return from kernel calls, and didn't really notice any effect
on performance in normal usage.
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