-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Somebody in the thread at some point said:
| # hdparm -tT /dev/sdg | | /dev/sdg: | Timing cached reads: 1286 MB in 2.00 seconds = 643.14 MB/sec | Timing buffered disk reads: 26 MB in 3.13 seconds = 8.32 MB/sec | # | | where /dev/sdg is a USB cardreader reading a uSD card. Obviously, | USB-2.0 is not able to provide 640MB/s so the cache is elsewhere. I eyeballed the hdparm sources, the difference between these guys is indeed meant to be the Linux block cache. In the cached read case it keeps seeking to 0 and doing a big read, in the noncached "buffered" case it keeps on reading new data and not seeking to zero. Hdparm does also concern itself with the drive cache but not directly in this test. If /dev/mmcblk0* was mounted at this time, maybe confirm the mount options used, eg, sync... I don't even know how to opt out of the buffer cache if we wanted to :-/ - -Andy -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iEYEARECAAYFAkkt0EoACgkQOjLpvpq7dMpM/gCfepFyo+hVAcoLARrscF2i3v2c O9cAnjiQEaDnIXijHcbe9IUS90C4tL1m =6g28 -----END PGP SIGNATURE-----
