Re: [PATCH 2/2] kcompressd: Add Kcompressd for accelerated zram compression

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (25/03/07 15:13), Nhat Pham wrote:
> > > +config KCOMPRESSD
> > > +       tristate "Kcompressd: Accelerated zram compression"
> > > +       depends on ZRAM
> > > +       help
> > > +         Kcompressd creates multiple daemons to accelerate the compression of pages
> > > +         in zram, offloading this time-consuming task from the zram driver.
> > > +
> > > +         This approach improves system efficiency by handling page compression separately,
> > > +         which was originally done by kswapd or direct reclaim.
> >
> > For direct reclaim, we were previously able to compress using multiple CPUs
> > with multi-threading.
> > After your patch, it seems that only a single thread/CPU is used for compression
> > so it won't necessarily improve direct reclaim performance?
> >
> > Even for kswapd, we used to have multiple threads like [kswapd0], [kswapd1],
> > and [kswapd2] for different nodes. Now, are we also limited to just one thread?
> > I also wonder if this could be handled at the vmscan level instead of the zram
> > level. then it might potentially help other sync devices or even zswap later.
> 
> Agree. A shared solution would be much appreciated. We can keep the
> kcompressd idea, but have it accept IO work from multiple sources
> (zram, zswap, whatever) through a shared API.

I guess it also need to take swapoff into consideration (especially
if it takes I/O from multiple sources)?