Lets make wifi fast again!
 help / color / mirror / Atom feed
From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Dave Taht <dave.taht@gmail.com>,  make-wifi-fast@lists.bufferbloat.net
Subject: Re: [Make-wifi-fast] a bit of profiling on the archer
Date: Fri, 18 Nov 2016 11:26:39 +0100	[thread overview]
Message-ID: <87zikxw0bk.fsf@toke.dk> (raw)
In-Reply-To: <20161118085524.62d6cfdd@redhat.com> (Jesper Dangaard Brouer's message of "Fri, 18 Nov 2016 08:55:24 +0100")

Jesper Dangaard Brouer <brouer@redhat.com> writes:

> On Thu, 17 Nov 2016 20:14:49 -0800 Dave Taht <dave.taht@gmail.com> wrote:
>
>> I have not been profiling much on lower end platforms (it's hard, you
>> can crash a box pretty easily with the wrong options or sample rates).
>
> I'm happy to hear that perf does work on this lower end HW, although
> the disclaimer of sample rates.
>
> Does anyone know if hardware based PMU (Performance Monitor Units)
> exists for these kind of devices?
>
>> While watching the ath10k peak at 150-200mbits, at 99% of cpu in
>> softirq, I spent a bit of time profiling various counters and
>> statistics.
>> 
>> for this one (while downloading 12 flows at the same time via flent)
>> 
>> perf record -F 99 -e cpu-clock -ag -- sleep 10
>> 
>> perf report
>
> Below perf report is not well suite for email, could you instead
> provide output from command below:
>
> perf report --no-children --stdio --call-graph none
>
>>
>>   [[31m  67.81%[[m     0.00%  ksoftirqd/0  [kernel.kallsyms]       [k]
>> run_ksoftirqd
>>             |
>>             ---run_ksoftirqd
>>                |
>>                |[[31m--67.61%-- [[m __do_softirq
>>                |          |
>>                |          |[[31m--66.80%-- [[m net_rx_action
>>                |          |          |
>>                |          |          |[[31m--41.07%-- [[m ag71xx_poll
>> 
>> ...
>
> (Looks like you managed to copy-paste the terminal escape codes for
> colors)
>
>> 
>> It appears we're spending 66% of the time in the *ethernet* portion of
>> the path.
>
> Be careful you don't fool yourself. In your output you have the
> "children" mode on, so everything being called "under" net_rx_action is
> summed up.  It could be it goes all the way through to the wifi TX
> parts and that is part of the sum.  Even the memory allocations gets
> summed into this 66% number.

Yes, actually my guess would be that this is the case. When I was
profiling ath9k I saw this exact behaviour.

-Toke

  reply	other threads:[~2016-11-18 10:26 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-18  4:14 Dave Taht
2016-11-18  7:55 ` Jesper Dangaard Brouer
2016-11-18 10:26   ` Toke Høiland-Jørgensen [this message]
2016-11-18 14:13   ` Eric Dumazet
2016-11-18 14:30     ` Toke Høiland-Jørgensen
2016-11-19 17:33   ` Dave Taht
2016-11-21 16:49     ` Jesper Dangaard Brouer
2016-11-19 18:30   ` Dave Taht
2016-11-21 16:24     ` Jesper Dangaard Brouer
2016-11-21 16:36       ` Jonathan Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://lists.bufferbloat.net/postorius/lists/make-wifi-fast.lists.bufferbloat.net/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87zikxw0bk.fsf@toke.dk \
    --to=toke@toke.dk \
    --cc=brouer@redhat.com \
    --cc=dave.taht@gmail.com \
    --cc=make-wifi-fast@lists.bufferbloat.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox