Poor read() performance, and I can't profile it
Kris Kennaway
kris at FreeBSD.org
Thu Jun 5 22:25:38 UTC 2008
Kirk Strauser wrote:
> On Thursday 05 June 2008, Kris Kennaway wrote:
>> Kirk Strauser wrote:
>
>> ktrace(1) and check for the buffer size in use. It is probably too
>> small.
>>
>> Kris
>
> It seems to be doing a lot of read()s with 4096-byte buffers. Is that what
> you mean? It's also doing a lot of lseek()s to what is likely the current
> position anyway (example: seek to 0x00, read 16 bytes, seek to 0x10, etc.).
> Would that make a difference, or should that be a NOP?
No, if it's reading in 16 byte units it will explain the terrible
performance.
Kris
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