On 3/30/2022 5:05 PM, Suzuki K Poulose wrote:
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 Maoquic_jinlmao@quicinc.com 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 Jinlongquic_jinlmao@quicinc.com >> --- >> 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
Hi Suzuki,
I will address your comments in next version.
Could you please help to review other patches ?
Thanks
Jinlong Mao
Thanks Jinlong Mao
Thanks
Jinlong Mao
Cheers Suzuki
> thanks, > > greg k-h Thanks
Jinlong Mao
CoreSight mailing list --coresight@lists.linaro.org To unsubscribe send an email tocoresight-leave@lists.linaro.org