linux-kernel - Re: [PATCHv4 14/17] zsmalloc: make zspage lock preemptible

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Message-ID: <huhxeq3k4q5lscj5xy6lldivku2wps6midxmt4swr67mce4nva@7mxupdxphs5a>
Date: Thu, 13 Feb 2025 16:21:32 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Kairui Song <ryncsn@...il.com>
Subject: Re: [PATCHv4 14/17] zsmalloc: make zspage lock preemptible

On (25/02/13 02:57), Yosry Ahmed wrote:
> > > I think we also need some high level testing (e.g. concurrent
> > >
> > >  swapins/swapouts) to find that out. I think that's what Kairui's testing
> > >
> > >  covers.
> > >
> >
> > I do a fair amount of high-level testing: heavy parallel (make -j36 and
> >
> > parallel dd) workloads (multiple zram devices configuration - zram0 ext4,
> >
> > zram1 writeback device, zram2 swap) w/ and w/o lockdep. In addition I also
> >
> > run these workloads under heavy memory pressure (a 4GB VM), when oom-killer
> >
> > starts to run around with a pair of scissors. But it's mostly regression
> >
> > testing.
> >

// JFI it seems your email client/service for some reason injects a lot
// of empty lines

> If we can get some numbers from these parallel workloads that would be better than the perf stats imo.

make -j24  CONFIG_PREEMPT


BASE
====

1363.64user 157.08system 1:30.89elapsed 1673%CPU (0avgtext+0avgdata 825692maxresident)k

lock stats

                              class name    con-bounces    contentions   waittime-min   waittime-max waittime-total   waittime-avg    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total   holdtime-avg
                   &pool->migrate_lock-R:             0              0           0.00           0.00           0.00           0.00          10001         702081           0.14         104.74      125571.64           0.18
                            &class->lock:             1              1           0.25           0.25           0.25           0.25           6320         840542           0.06         809.72      191214.87           0.23
                         &zspage->lock-R:             0              0           0.00           0.00           0.00           0.00           6452         664129           0.12         660.24      201888.61           0.30
                &zram->table[index].lock:             0              0           0.00           0.00           0.00           0.00        1716362        3096466           0.07         811.10      365551.24           0.12
                            &zstrm->lock:             0              0           0.00           0.00           0.00           0.00              0         664129           1.68        1004.80    14853571.32          22.37

PATCHED
=======

1366.50user 154.89system 1:30.33elapsed 1684%CPU (0avgtext+0avgdata 825692maxresident)k

lock stats

                              class name    con-bounces    contentions   waittime-min   waittime-max waittime-total   waittime-avg    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total   holdtime-avg
                         &pool->lock#3-R:             0              0           0.00           0.00           0.00           0.00           3648         701979           0.12          44.09      107333.02           0.15
                            &class->lock:             0              0           0.00           0.00           0.00           0.00           5038         840434           0.06        1245.90      211814.60           0.25
                         zsmalloc-page-R:             0              0           0.00           0.00           0.00           0.00              0         664078           0.05         699.35      236641.75           0.36
                        zram-entry->lock:             0              0           0.00           0.00           0.00           0.00              0        3098328           0.06        2987.02      313339.11           0.10
   &per_cpu_ptr(comp->stream, cpu)->lock:             0              0           0.00           0.00           0.00           0.00             23         664078           1.77        7071.30    14838397.61          22.34