Re: [PATCH 00/10] zram: various improvements and cleanups

Greg KH
2010-08-31T22:38:41Z

On Mon, Aug 09, 2010 at 10:56:46PM +0530, Nitin Gupta wrote:
> The zram module creates RAM based block devices named /dev/zram<id>
> (<id> = 0, 1, ...). Pages written to these disks are compressed and stored
> in memory itself.
>
> One of the major changes done is the replacement of ioctls with sysfs
> interface. One of the advantages of this approach is we no longer depend on the
> userspace tool (rzscontrol) which was used to set various parameters and check
> statistics. Maintaining updated version of rzscontrol as changes were done to
> ioctls, statistics exported etc. was a major pain.
>
> Another significant change is the introduction of percpu stats and compression
> buffers. Earlier, we had per-device buffers protected by a mutex. This was a
> major bottleneck on multi-core systems. With these changes, benchmarks with
> fio[1] showed a speedup of about 20% for write performance on dual-core
> system (see patch 4/10 description for details).
>
>
> For easier testing, a single patch against 2.6.35-git8 has been uploaded at:
> http://compcache.googlecode.com/hg/sub-projects/mainline/zram_2.6.36-rc0.patch

I applied the first 2 and last 2 of these patches and they will show up
in the linux-next tree tomorrow. I stopped there due to Andrew's
complaints about the per-cpu variable stuff. Please resolve this and
redo the patch set and I will be glad to apply them.

thanks,

greg k-h