On 30/03/2022 03:10, Jinlong Mao wrote:
On 3/29/2022 10:36 PM, Mathieu Poirier wrote:
On Tue, 29 Mar 2022 at 07:56, Jinlong Mao<quic_jinlmao@xxxxxxxxxxx> wrote:
Hi Suzuki,
On 3/28/2022 4:33 PM, Suzuki K Poulose wrote:
On 24/03/2022 14:23, 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.
Where do we use sequential search now ? For non-CPU bound sources, yes
we may need something. But CPU case is straight forward, and could be
retained as it is. i.e., per-cpu list of paths.
We use list to store the paths for both ETM and non-CPU bound sources in
patch below.
“[PATCH 01/10] coresight: add support to enable more coresight paths”
According to Mathieu's comments, IDR is used now. So i added "Using IDR
will be more efficient than using
the list" this message in my commit message. I think we need to use one
mechanism to store ETM and
non-CPU bound sources.
Mathieu's comments:
So many TPDM and many ETMs... That is definitely a reason to do better than a
sequential search.
If an IDR (or some other kind of mechanism) is used then we can use that to
store paths associated with ETMs as well. That way everything works the same
way and access time is constant for any kind of source.
As per my last sentence above, the goal of my comment was to simplify
things so that we don't have two different ways of managing sources.
But if that ends up causing more trouble than benefit then it should
be avoided.
Hi Mathieu,
I didn't see any disadvantage to use IDR to store both ETM source and
non-CPU bound sources.
Benefits:
* Only need to maintain one way of managing sources.
* Less time to search the path
My preference is to keep the ETM source paths per-CPU. For the reasons
below :
- It is straight forward for an ETM. per_cpu(paths, cpu)
- It is faster than the IDR.
- Makes the debugging easier. Simply lookup the per_cpu variable.
I agree that the IDR is required for the non ETM sources. And I am fine
with that.
Suzuki
Thanks
Jinlong Mao
Thanks
Jinlong Mao
Cheers
Suzuki
thanks,
greg k-h
Thanks
Jinlong Mao
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