Re: [linux-next:master] [memcg] 70a64b7919: will-it-scale.per_process_ops -11.9% regression

[Shakeel Butt <shakeel.butt@linux.dev>]

On Fri, May 24, 2024 at 03:45:54PM +0800, Oliver Sang wrote:
> hi, Shakeel,
> 
[...]
> 
> > 
> > 1. What is the baseline kernel you are using? Is it linux-next or linus?
> > If linux-next, which one specifically?
> 
> base is just 59142d87ab03b, which is in current linux-next/master,
> and is already merged into linus/master now.
> 
> linux$ git rev-list linux-next/master | grep 59142d87ab03b
> 59142d87ab03b8ff969074348f65730d465f42ee
> 
> linux$ git rev-list linus/master | grep 59142d87ab03b
> 59142d87ab03b8ff969074348f65730d465f42ee
> 
> 
> the data for it is the first column in the tables we supplied.
> 
> I just applied your patch upon a94032b35e5f9, so:
> 
> linux$ git log --oneline --graph fd2296741e2686ed6ecd05187e4
> * fd2296741e268 fix for 70a64b7919 from Shakeel  <----- your fix patch
> * a94032b35e5f9 memcg: use proper type for mod_memcg_state   <--- patch-set tip, I believe
> * acb5fe2f1aff0 memcg: warn for unexpected events and stats
> * 4715c6a753dcc mm: cleanup WORKINGSET_NODES in workingset
> * 0667c7870a186 memcg: cleanup __mod_memcg_lruvec_state
> * ff48c71c26aae memcg: reduce memory for the lruvec and memcg stats
> * aab6103b97f1c mm: memcg: account memory used for memcg vmstats and lruvec stats
> * 70a64b7919cbd memcg: dynamically allocate lruvec_stats   <--- we reported this as 'fbc' in original report
> * 59142d87ab03b memcg: reduce memory size of mem_cgroup_events_index   <--- base
> 

Cool, let's stick to the linus tree. I was actually taking next-20240521
and reverting all the patches in the series to treat as the base. One
request I have would be to make the base the patch previous to the
59142d87ab03b i.e. not 59142d87ab03b.

> 
> > 
> > 2. What is the cgroup hierarchy where the workload is running? Is it
> > running in the root cgroup?
> 
> Our test system uses systemd from the distribution (debian-12). The workload is
> automatically assigned to a specific cgroup by systemd which is in the
> sub-hierarchy of root, so it is not directly running in the root cgroup.
> 
> > 
> > 3. For the followup experiments when needed, can you please remove the
> > whole series (including 59142d87ab03b8ff) for the base numbers.
> 
> I cannot understand this very well, if the patch is to fix the regression
> cause by this series, seems to me the best way is to apply this patch on top
> of the series. anything I misunderstood here?
> 

Sorry I just meant to make the 'base' case to compare against the commit
previous to 59142d87ab03b as I said above.

I will re-run my experiments on linus tree and report back.