On Sat, 26 Feb 2000, Dimitris Michailidis wrote:
>This was MP (4 Xeon @500MHz). As another data point, on the same machine,
>dbench 32 has a throughput of about 42MB/s with 2.3.40. With stock 2.3.47
>it's just under 7MB/s and the CPUs have a much lower utilization (27% out of
>the 4 CPUs versus 100+% with 2.3.40).
How much memory for cache do you have? Please try again after:
echo 95 > /proc/sys/vm/bdflush
In the latest kernels I fixed a dirty memory balance issue that wasn't
harming in real life but that was potentially harmful.
Increasing the percentage of memory that can be dirty should emulate the
old behaviour.
You can also want to monitor how much I/O happens with 2.3.40 and how much
I/O happens with 2.3.47 (or 2.3.48). If the I/O going on with 2.3.48 is
much more than 2.3.40 that is dirty-cache size issue is probably the
interesting change. Increasing the memory on the machine will help too of
course.
If that wasn't the problem please let me know about the details of you HD
hardware (IDE/SCSI) and if possible also show me a `vmstat 1` during the
test first with 2.3.40 and then with 2.3.48. Thanks!
Andrea
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