Re: Higher than expected disk write(2) latency

[Martin Sustrik]

David Newall wrote:
> Martin Lucina wrote:
> > Measurement of the write(2) time is performed using the TSC, so any
> > latency there is negligible.
>
> Measuring each write is lavish and bound to impact the results.  To
> measure sustained throughput, get the time only at start and end, and
> divide the difference by the number of writes.

Hi,

We're using RDTSC to measure time, which takes ~30 nanoseconds to 
complete. I would say this is negligible given that latency of a write 
is 5 orders of magnitude higher.

Martin

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