Subject: Re: [linux-audio-dev] hdr disk throughput
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Tue Mar 14 2000 - 16:30:07 EST
On Tue, 14 Mar 2000, David Jander wrote:
> Now, on a software RAID0 partition (both drives together):
> Total time: 13 seconds
> Throughput: 9.846154 Mb/s (way too cool for this poor system)
>
> Until now you can get a hint about software RAID0 performance :-)
> And my test machine is still very poor performing (AMD-K5+IDE disks) !!
> The really weired thing arises when I use this program as regular user (non
> root, non-raid), PLEASE CHECK THIS:
> Total time: 6 seconds
> Throughput: 21.333333 Mb/s (??????)
>
> What's possibly going on here ? I'll have to figure that out. But it means,
> your little hack is not always reliable. The file (aprox. 134 Mb) is created in
> that short time although.
>
> yours,
very simple:
very probably you are victim of the buffer cache
:-)
since you have 64MB RAM and write only 134MB, it
could happen that sometimes the application returns just after it has written
the about 60MB to disk, because the rest is buffered in RAM
(and written when the kernel syncs buffers to disk, after a few secs)
solution:
use 300-500MB for more reliable results.
( RAID0 may show up a different buffering behaviour than
regular disks)
just my 2c
Benno.
This archive was generated by hypermail 2b28 : Wed Mar 15 2000 - 00:20:51 EST