From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Walker Subject: Re: problem w/ read caching.. Date: Mon, 1 Oct 2012 20:56:21 +0000 (UTC) Message-ID: References: <20120928185949.GA7062@google.com> <20121001193806.GA26488@google.com> <20121001203706.GB26488@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org Kent Overstreet writes: > > On Mon, Oct 01, 2012 at 08:05:14PM +0000, Brad Walker wrote: > > Kent Overstreet writes: > > > > > > > > What about cache_bypass_hits, cache_bypass_misses? > > > > > > > cache_bypass_hits = 0 > > cache_bypass_misses = 0 > > I should've just asked you for all the stats - what about > cache_miss_collision? bwalker:/sys/fs/bcache/dd10d09c-0605-462c-af85-8466b0aa2017/stats_total> ls bypassed cache_bypass_misses cache_hits cache_misses cache_bypass_hits cache_hit_ratio cache_miss_collisions cache_readaheads bwalker:/sys/fs/bcache/dd10d09c-0605-462c-af85-8466b0aa2017/stats_total> cat * 0 0 0 98 162315691 0 2329081 0 bwalker:/sys/fs/bcache/dd10d09c-0605-462c-af85-8466b0aa2017/stats_total> > Also, internal/cache_read_races? cat /sys/fs/bcache/dd10d09c-0605-462c-af85-8466b0aa2017/interna/cache_read_races 0 > Perhaps stuff is getting evicted from the cache for some reason... How > big is the SSD? nellis: # sg_inq /dev/rssda ATA device: model, serial number and firmware revision: Micron P320h-MTFDGAR350SAH 000000001143020287B2 B1490300 nellis: # fdisk /dev/rssda The device presents a logical sector size that is smaller than the physical sector size. Aligning to a physical sector (or optimal I/O) size boundary is recommended, or performance may be impacted. Command (m for help): p Disk /dev/rssda: 350.1 GB, 350078754816 bytes 210 heads, 56 sectors/track, 58141 cylinders, total 683747568 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x16e1596f Device Boot Start End Blocks Id System /dev/rssda1 2048 683747567 341872760 83 Linux Command (m for help): > Is cache_replacement_policy lru? (the default - cache_replacement_policy > is in cache0/) LRU > What's cache0/priority_stats say? > nellis: # cat priority_stats Unused: 97% Metadata: 0% Average: 0 Sectors per Q: 582336 Quantiles: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1] nellis: #