Linux Read-Ahead Downsides
- by JPerkSter
Hi Everyone,
Hope all is well. I have a question regarding read-ahead caching.
Are there any downsides to raising the size of the read-ahead cache?
On our farm, we're currently running at 256, and upon raising that higher, we are seeing significant throughput gains.
[root@server~]# hdparm -tT /dev/sda /dev/sda:
Timing cached reads: 7352 MB in 2.00 seconds = 3677.62 MB/sec 3
Timing buffered disk reads: 244 MB in 3.10 seconds = 78.68 MB/sec
[root@server ~]# blockdev --setra 10240 /dev/sda
[root@server ~]# hdparm -tT /dev/sda /dev/sda:
Timing cached reads: 11452 MB in 2.00 seconds = 5728.52 MB/sec
Timing buffered disk reads: 422 MB in 3.17 seconds = 133.04 MB/sec
We are running on 2.6. Thanks!
