Hi Greg,
On 3/25/2022 1:06 AM, Greg Kroah-Hartman wrote:
On Thu, Mar 24, 2022 at 10:23:19PM +0800, Jinlong Mao wrote:
Hi Greg,
Thanks for your review.
On 3/24/2022 8:26 PM, Greg Kroah-Hartman wrote:
On Thu, Mar 24, 2022 at 08:17:25PM +0800, Mao Jinlong wrote:
Use hash length of the source's device name to map to the pointer
of the enabled path. Using IDR will be more efficient than using
the list. And there could be other sources except STM and CPU etms
in the new HWs. It is better to maintain all the paths together.
Signed-off-by: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
---
drivers/hwtracing/coresight/coresight-core.c | 75 +++++++-------------
1 file changed, 26 insertions(+), 49 deletions(-)
Your subject line is odd. Please put back the driver subsystem in the
subject line so that it makes more sense.
I will update the subject in next version.
And how have you measured "more efficient"?
Using IDR would be better than doing a sequential search as there will be
much more device in future.
How many "more"? Where does the trade off of speed for complexity help?
How much faster is this really? You can't claim performance
improvements without any proof :)
There is about 40 trace sources in our internal device. I believe there
will be more cpu cores, then
there will be more etm sources. IDR here is used to store the path of
both etm
sources and other sources which aren't associated with CPU. Use IDR is
not more complicated
than using list. It will also save the time of searching the path when
coresight_disable.
I tested in internal device. The test case is that enable all the
sources, disable the source one
by one to check the search time.
Use list to store paths:
sh-7687 [005] .... 342.113099: __coresight_disable:
====search path start==== source_0
sh-7687 [005] .... 342.113127: __coresight_disable:
====search path end==== source_0
sh-7693 [005] .... 342.542216: __coresight_disable:
====search path start==== source_1
sh-7693 [005] .... 342.542244: __coresight_disable:
====search path end==== source_1
sh-7699 [005] .... 342.929083: __coresight_disable:
====search path start==== source_2
sh-7699 [005] .... 342.929106: __coresight_disable:
====search path end==== source_2
sh-7711 [005] .... 343.760688: __coresight_disable:
====search path start==== source_3
sh-7711 [005] .... 343.760713: __coresight_disable:
====search path end==== source_3
sh-7717 [005] .... 344.172353: __coresight_disable:
====search path start==== source_4
sh-7717 [005] .... 344.172381: __coresight_disable:
====search path end==== source_4
Use IDR to store paths:
sh-7156 [006] .... 223.294228: __coresight_disable:
====search path start==== source_0
sh-7156 [006] .... 223.294237: __coresight_disable:
====search path end==== source_0
sh-7162 [006] .... 223.690153: __coresight_disable:
====search path start==== source_1
sh-7162 [006] .... 223.690163: __coresight_disable:
====search path end==== source_1
sh-7168 [006] .... 224.110670: __coresight_disable:
====search path start==== source_2
sh-7168 [006] .... 224.110679: __coresight_disable:
====search path end==== source_2
<...>-7180 [006] .... 224.929315: __coresight_disable:
====search path start==== source_3
<...>-7180 [006] .... 224.929324: __coresight_disable:
====search path end==== source_3
<...>-7186 [006] .... 225.343617: __coresight_disable:
====search path start==== source_4
<...>-7186 [006] .... 225.343626: __coresight_disable:
====search path end==== source_4
From the log, Searching the path from the IDR takes about 9us for each
source.
Searching the path from the list takes about 23 ~ 28us for the source.
Use IDR saves much time.
Thanks
Jinlong Mao
thanks,
greg k-h
