Andrew Theurer wrote:
Avi Kivity wrote:
Anthony Liguori wrote:
Avi Kivity wrote:
1) I'm seeing about 2.3% in scheduler functions [that I recognize].
Does that seems a bit excessive?
Yes, it is. If there is a lot of I/O, this might be due to the
thread pool used for I/O.
This is why I wrote the linux-aio patch. It only reduced CPU
consumption by about 2% although I'm not sure if that's absolute or
relative. Andrew?
If I recall correctly, it was 2.4% and relative. But with 2.3% in
scheduler functions, that's what I expected.
Was that before or after the entire path was made copyless?
If this is referring to the preadv/writev support, no, I have not
tested with that.
Previously, the block API only exposed non-vector interfaces and bounced
vectored operations to a linear buffer. That's been eliminated now
though so we need to update the linux-aio patch to implement a vectored
backend interface.
However, it is an apples to apples comparison in terms of copying since
the same is true with the thread pool. My take away was that the thread
pool overhead isn't the major source of issues.
Regards,
Anthony Liguori
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