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Re: Unexpectedly low read/write performance of open-pipe

From: Rob Browning
Subject: Re: Unexpectedly low read/write performance of open-pipe
Date: Sun, 07 Apr 2019 14:47:31 -0500

Rob Browning <address@hidden> writes:

> For what it's worth, in an earlier round of testing I also hacked up
> open-pipe to let me access the underlying ports and set their buffers to
> 65k.  That doubled the transfer rate, but of course, it's still fairly
> slow.

I also ran statprof on the OPEN_BOTH case and saw that the majority of
the time was spent in read-char (guessing via the open-pipe soft-port).
I also observed that the machine's fan spun up during the OPEN_BOTH test
(presumably due to high CPU use).

I haven't tried to track it down yet, but if the only underlying way to
get a fixed block of data out of an OPEN_BOTH port is read-char, then
that might explain much of the difference.

Rob Browning
rlb and
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