lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Doug Cutting <cutt...@apache.org>
Subject Re: detected corrupted index / performance improvement
Date Fri, 08 Feb 2008 19:28:45 GMT
Doug Cutting wrote:
> The linux 
> kernel dynamically increases the readahead window based on the access 
> pattern: the more you read sequentially, the larger the readahead window.

Sorry, it appears that's in 2.6.23, which isn't yet broadly used.

http://kernelnewbies.org/Linux_2_6_23#head-102af265937262a7a21766ae58fddc1a29a5d8d7

In the meantime, on Linux, one can set both the kernel's readahead 
buffer size and the device's.  These are additive: the first determines 
what requests will be made to the device, the second determines how much 
beyond that the device will attempt to read.

# set kernel read-ahead buffer to 1MB
echo 1024 > /sys/block/sda/queue/read_ahead_kb

# set device read-ahead buffer to 1024 sectors
hdparm -a1024 /dev/sda1

I don't know how much these actually help things...

Doug

---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org


Mime
View raw message