Re: [PATCH v7 0/2] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi

[Alexey Budankov]

Hi,
On 22.08.2017 23:21, Peter Zijlstra wrote:
> On Fri, Aug 18, 2017 at 08:17:15AM +0300, Alexey Budankov wrote:
>> Hi,
> 
> Please don't post new versions in reply to old versions, that gets them
> lost in thread sorted views.
> 
>> This patch set v7 moves event groups into rb trees and implements 
>> skipping to the current CPU's list on hrtimer interrupt.
> 
> Does this depend on your timekeeping rework posted in that v6 thread?
> If so, I would have expected to see that as part of these patches, if
> not, I'm confused, because part of the problem was that we currently
> need to update times for events we don't want to schedule etc..
> 
>> Events allocated for the same CPU are still kept in a linked list
>> of the event directly attached to the tree because it is unclear 
>> how to implement fast iteration thru events allocated for 
>> the same CPU when they are all attached to a tree employing 
>> additional 64bit index as a secondary treee key.
> 
> Finding the CPU subtree and rb_next() wasn't good?

I eventually managed to overcome difficulties with implementation
of rb_tree indexed by {cpu,index} for event groups so please 
see patches v9.

> 
> 
>