On Jan 11, 2007, at 3:28 PM, Scott Atchley wrote:
On Jan 11, 2007, at 2:47 PM, Sam Lang wrote:
So this 11 msec delay could be caused by writing to disk, but if
you don't have data sync enabled (which I don't think you do),
then 11 msec for 1 MB is about 90MB/s to write data to buffer
cache and return the write ack response. We might be delayed
here by having to wait for flow buffers being free'd up from one
of the first 8 1MB messages. Could you increase the
FlowBuffersPerFlow option in the fs.conf to 16 or 20 and see
what happens?
-sam
I will try this.
I know that the default for FlowBuffersPerFlow is 8 per the
webpage, but I count 10 per flow in the log. I also find that
when using the -b flag, that it performs best with multiples of
10 buffers.
You're doing 10MB requests with 1MB flow buffers. I think the 10
flows per request are from that, so the number of flow buffers is
still 8, it just has to reuse 2 of them.
-b specifies the request size doesn't it? Using multiples of 10
for that value improves performance? I really have no idea, but
would have guessed that multiples of the flow buffer size (in your
case 1MB) would have been better.
-sam
With FlowBuffersPerFlow set to 20, I am roughly the same gaps as
before (~11 msec between last send completion and the recv
completion and ~18 msec between transfers).
Scott
On the server, I am seeing the exact same values. ~11 msec between
the completion of the last recv before sending the ack and ~18 msec
between sending the ack and the unexpected recv to start the next
transfer.
Scott
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