On 02/03/2013 07:03 PM, Simon Jeons wrote: > On Fri, 2013-02-01 at 09:13 -0600, Seth Jennings wrote: >> On 01/31/2013 07:39 PM, Simon Jeons wrote: >>> Hi Seth, >>> On Tue, 2013-01-29 at 15:40 -0600, Seth Jennings wrote: >> <snip> >>>> Performance, Kernel Building: >>>> >>>> Setup >>>> ======== >>>> Gentoo w/ kernel v3.7-rc7 >>>> Quad-core i5-2500 @ 3.3GHz >>>> 512MB DDR3 1600MHz (limited with mem=512m on boot) >>>> Filesystem and swap on 80GB HDD (about 58MB/s with hdparm -t) >>>> majflt are major page faults reported by the time command >>>> pswpin/out is the delta of pswpin/out from /proc/vmstat before and after >>>> then make -jN >>>> >>>> Summary >>>> ======== >>>> * Zswap reduces I/O and improves performance at all swap pressure levels. >>>> >>>> * Under heavy swaping at 24 threads, zswap reduced I/O by 76%, saving >>>> over 1.5GB of I/O, and cut runtime in half. >>> >>> How to get your benchmark? >> >> It's just kernel building. So "make" :) >> >> I intentionally choose this workload so people wouldn't have to jump >> through hoops to replicate the results. > > Since there already have zram which can handle anonymous pages > compression, why need zswap? What's the difference of design between > zram and zswap?
zram is implemented is a virtual block device. It interfaces with the block device layer, not the swap code. In fact, zram can be used as a generic compressed RAM disk, not only for compressed swap. One can think of it as a RAM disk + compression. So zram is the actual swap device while zswap is a caching layer above the swap device. zswap is not the swap device itself like zram. Hope this clears up the difference :) Seth -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
