lkml.org 
[lkml]   [2013]   [Oct]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2] can: c_can: Speed up rx_poll function
From
Date
On Tue, 2013-10-29 at 09:58 +0100, Markus Pargmann wrote:
> On Tue, Oct 29, 2013 at 01:34:48AM -0700, Joe Perches wrote:
> > On Tue, 2013-10-29 at 09:27 +0100, Markus Pargmann wrote:
> > > This patch speeds up the rx_poll function by reducing the number of
> > > register reads.
> > []
> > > 125kbit:
> > > Function Hit Time Avg s^2
> > > -------- --- ---- --- ---
> > > c_can_do_rx_poll 63960 10168178 us 158.977 us 1493056 us
> > > With patch:
> > > c_can_do_rx_poll 63939 4268457 us 66.758 us 818790.9 us
> > >
> > > 1Mbit:
> > > Function Hit Time Avg s^2
> > > -------- --- ---- --- ---
> > > c_can_do_rx_poll 69489 30049498 us 432.435 us 9271851 us
> > > With patch:
> > > c_can_do_rx_poll 103034 24220362 us 235.071 us 6016656 us
[]
> Yes I just measured the timings again:
[]
> ./perf_can_test.sh 125000 30
[]
> c_can_do_rx_poll 63941 3764057 us 58.867 us 776162.2 us

Good, it's slightly faster still.

> ./perf_can_test.sh 1000000 30
[]
> c_can_do_rx_poll 207109 24322185 us 117.436 us 171469047 us
[]
> It is interesting that the number of hits for c_can_do_rx_poll is twice as much
> as it was with find_next_bit.

How is this possible? Any idea?




\
 
 \ /
  Last update: 2013-10-29 18:01    [W:0.248 / U:1.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site