On Sun, Jan 08, 2012 at 10:21:50PM +0000, Poul-Henning Kamp wrote: > > I'm doing som data-mining on a pile of ISO images right now. > > I stuck the ISOs on a UFS2 on a flash-disk for speed, and mdconfig(8)'d > them so I could mount them. > > The traffic pattern his "interesting": > > dT: 1.003s w: 1.000s > L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name > [...] > 1 733 733 1466 1.3 0 0 0.0 98.2| md39 > 1 733 733 23449 1.3 0 0 0.0 93.2| da0 > > Notice the 1:16 ratio on kBps but 1:1 ratio on ops/s ? > > da0's UFS2 has 32k block-size: > > magic 19540119 (UFS2) time Wed Jan 4 16:41:47 2012 > superblock location 65536 id [ 4f046cf5 c30697ee ] > ncg 104 size 19537685 blocks 19228156 > bsize 32768 shift 15 mask 0xffff8000 > fsize 4096 shift 12 mask 0xfffff000 > [...] > > It looks like every 2k read from CD9660 turns into a 32k block > read in the UFS filesystem, without any beneficial caching happening. > > Less than optimal I'd say... > What is the access patern ? Is it random access, or sequential read (from the cd9660 POV) ?
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