Hi Dan, On Sat, Dec 8, 2012 at 7:57 AM, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> wrote: > While playing around with zcache+zram (see separate thread), > I was watching stats with "watch -d". > > It appears from the code that /sys/block/num_writes only > increases, never decreases. In my test, num_writes got up > to 1863. /sys/block/disksize is 104857600. > > I have two swap disks, one zram (pri=60), one real (pri=-1), > and as a I watched /proc/swaps, the "Used" field grew rapidly > and reached the Size (102396k) of the zram swap, and then > the second swap disk (a physical disk partition) started being > used. Then for awhile, the Used field for both swap devices > was changing (up and down). > > Can you explain how this could happen if num_writes never > exceeded 1863? This may be harmless in the case where > the only swap on the system is zram; or may indicate a bug > somewhere? > Sorry, I didn't get your idea here. In my opinion, num_writes is the count of request but not the size. I think the total size should be the sum of bio->bi_size, so if num_writes is 1863 the actual size may also exceed 102396k. > It looks like num_writes is counting bio's not pages... > which would imply the bio's are potentially quite large > (and I'll guess they are of size SWAPFILE_CLUSTER which is > defined to be 256). Do large clusters make sense with zram? > > Late on a Friday so sorry if I am incomprehensible... > > P.S. The corresponding stat for zcache indicates that > it failed 8852 stores, so I would have expected zram > to deal with no more than 8852 compressions. > -- Regards, --Bob -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>