Classic running out of memory... huh? what? <long>
Bruce Labitt
bruce.labitt at myfairpoint.net
Thu Jun 11 19:30:54 EDT 2009
But all this doesn't help the OP at all. The OP should benchmark
> the performance of what he's got. It doesn't really matter if X could
> be faster if his particular X is slow.
>
> -- Ben
>
OP here... That 45 MB/sec file write rate was real-world, using fwrite
in C over a network. The average write rate was 45MB/sec with peaks
nearly hitting the full gbit ethernet bandwidth. This was for a 11.9GB
file. (I have 10 files to write.) It took about 4.5 minutes for the
file write. Standard MTU size. I have not messed with jumbo packets in
a while. I had jumbo frames running for a little while and then I
messed something up. Probably time to implement jumbo frames now that
my program seems to be running.
NFS server on Ubuntu 8.10 - cheap workstation - 8GB RAM - 300GB fast
SATA drive, 1TB slower SATA drive. NFS client - diskless QS22.
Using netperf I think I got 770e6 bps write rates, but for considerably
smaller file sizes. That is about twice the rate - but for a file at
least 10 times smaller. Something about these big file writes that
aggrevate OS's :-)
Although it would be fun to benchmark alternative storage schemes, that
wasn't the original problem... I was running out of memory, getting the
OOM error and having the process killed. I have seemingly dodged the
problem by further constraining the buffer allocation. It is now at a
mere 12GB. When I left work the sim had been run for 6.5 hours and it
appeared I was thru the "danger" region. We shall know for sure in the
morning.
I will run valgrind on a smaller problem to see what is going on.
-Bruce
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