On 07/23/2013 07:53 PM, Greg Kroah-Hartman wrote:
On Sat, Jun 15, 2013 at 10:04:26AM -0400, Peter Hurley wrote:
Byte-by-byte echo output is painfully slow, requiring a lock/unlock
cycle for every input byte.
Instead, perform the echo output in blocks of 256 characters, and
at least once per flip buffer receive. Enough space is reserved in
the echo buffer to guarantee a full block can be saved without
overrunning the echo output. Overrun is prevented by discarding
the oldest echoes until enough space exists in the echo buffer
to receive at least a full block of new echoes.
I'm a bit worried about this, I wonder if anything is expecting the
echos to not come in "bursts" like this, but I really can't think of why
they would want that.
The block size for echoes is trivially settable so if you'd prefer a
smaller value than every 256 chars, I could send a patch for a value
you are more comfortable with - 64 chars, 32 chars, whatever.
I picked that value from casual performance testing and that it
coincides with the smallest possible flip buffer; ie., echo blocks are
retired at the same rate as flip buffers when receiving is not
saturated.
So let's apply it and see what breaks! :)
I'm ready :)
Regards,
Peter Hurley
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