That sounds like your SSD is slow and bottlenecking you... What kind of SSD is it? Could be some strange plugging thing, maybe... On Tue, Feb 14, 2012 at 11:16 PM, Franco <franco@xxxxxxxxxxxxxxxx> wrote: > > I did a reboot and got it registered again. > > bio: create slab <bio-1> at 1 > bcache: invalidating existing data > bcache: registered cache device sdb > bcache: Caching sdc, inserted new UUID 87ba7904-7690-4985-b6a8-daeba41712a3 > EXT4-fs (bcache0): mounted filesystem with ordered data mode. Opts: (null) > > > First read went at 119 MB/Sec, second at 37MB/Sec > > Here's what's in stats_hour > > /sys/block/sdc/bcache/stats_hour/cache_bypass_hits > :::::::::::::: > 44 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_bypass_misses > :::::::::::::: > 81172 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_hit_ratio > :::::::::::::: > 0 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_hits > :::::::::::::: > 24 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_miss_collisions > :::::::::::::: > 14 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_misses > :::::::::::::: > 407422 > :::::::::::::: > /sys/block/sdc/bcache/stats_hour/cache_readaheads > :::::::::::::: > 0 > > With echo 0 >/sys/block/sdc/bcache/sequential_cutoff > > 33 MB/Sec > > > On Tue, 2012-02-14 at 22:24 -0800, Kent Overstreet wrote: >> Not sure what's going on with not being able to register again - not a >> lot of info to go off of. It was working last I checked in the >> bcache-3.2-dev branch, it might be buggy in the older bcache branch. >> >> >From your numbers it looks like the 8 gb of data wasn't in the cache - >> bcache bypasses sequential IO by default. You can flip it off by >> echoing 0 to sequential_cutoff. >> >> On Tue, Feb 14, 2012 at 9:26 PM, Franco <franco@xxxxxxxxxxxxxxxx> wrote: >> > Hi >> > >> > I was in the process of testing linux-bcache but was seeing some strange >> > behaviour so I thought I would remount my cached filesystem. I then >> > noticed that the performance results started looking like the cache just >> > wasn't there, so I unregistered it: >> > >> > bcache: Cache set be008612-38aa-4082-9f42-1bada25cb002 unregistered >> > bcache: Caching disabled for sdc >> > >> > but now when I try to register it again, I get bcache: error >> > opening /dev/sdb: device busy. >> > >> > I haven't tried rebooting yet but probably will do after I've sent this >> > message. >> > >> > These were the strange results I was getting that prompted me to unmount >> > and remount the filesystems. >> > >> > Setup: hardware RAID 5 16 disk array with 2 partitions, 1 Intel 40GB SSD >> > for bcache. >> > >> > Filesystem Size Used Avail Use% Mounted on >> > /dev/bcache0 1.9T 26G 1.8T 2% /data33 >> > /dev/sdd 1.9T 23G 1.8T 2% /data34 >> > >> > Wrote an 8GB file to each filesystem, then tried reading it back. >> > Machine has 8GB RAM. >> > >> > Speed for random reads from identical SSD = 181.766523 MB/Sec, random >> > read test done in the following order with measured speed in MB/Sec. The >> > random IO is actually just reading with a 4GB stride, wrapping around at >> > the end of the file. >> > >> > /data33 49 >> > /data34 114 >> > /data33 114 >> > /data33 and /data44 simultaneously 78 and 59 respectively >> > /data33 76 >> > /data33 68 >> > /data34 114 >> > /data34 96 >> > /data34 69 >> > /data34 74 >> > /data33 118 >> > /data33 40 >> > /data34 91 >> > >> > After remounting both filesystems: >> > >> > /data34 148 >> > /data33 120 >> > /data34 120 >> > /data33 82 >> > >> > >> > After unregistering the cache >> > >> > /data33 65 >> > /data34 83 >> > /data33 99 >> > /data34 113 >> > >> > Cheers, >> > Franco >> > >> > >> > -- >> > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in >> > the body of a message to majordomo@xxxxxxxxxxxxxxx >> > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
