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| author | bde <bde@FreeBSD.org> | 1998-08-18 03:54:39 +0000 |
|---|---|---|
| committer | bde <bde@FreeBSD.org> | 1998-08-18 03:54:39 +0000 |
| commit | 605f4cb33bb28225fcbe534bb74245be8ad29185 (patch) | |
| tree | 109a7cecda2a9e3df0d2cdc55a84655fcdff9136 /sys/dev/syscons/syscons.c | |
| parent | 7300b9a59ccdfc6e3f55a4eb03f9b938808b4fc9 (diff) | |
| download | FreeBSD-src-605f4cb33bb28225fcbe534bb74245be8ad29185.zip FreeBSD-src-605f4cb33bb28225fcbe534bb74245be8ad29185.tar.gz | |
Quick fix for breakage of read clustering on non-IDE drives. Read
clustering is obsolescent technology so hardly anyone noticed. On
a DORS 32160 SCSI drive with 4 tags, read clustering makes very
little difference even for huge sequential reads. However, on a
ZIP SCSI drive with 0 tags, the minimum overhead per block is about
40 msec, so very large clusters must be used to get anywhere near
the maximum transfer rate. Using clusters consisting of 1 8K block
reduces the transfer rate to about 250K/sec. Under msdosfs, missing
read clustering is normal and a cluster size of 1 512 byte block
reduces the transfer rate to about 25K/sec.
Broken in: rev.1.18
Diffstat (limited to 'sys/dev/syscons/syscons.c')
0 files changed, 0 insertions, 0 deletions
