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Re: [Nmh-workers] Pessimal Optimizations.

From: Lyndon Nerenberg
Subject: Re: [Nmh-workers] Pessimal Optimizations.
Date: Tue, 11 Dec 2012 18:11:44 -0800

On 2012-12-11, at 6:04 PM, Ken Hornstein wrote:

> So, think about the data flow for a second. mhl reads the body of the
> message in (using m_getfld()!) and then writes it to a pipe. replyfilter
> reads it from the pipe and then processes it.  So we're talking about
> a stdio read, a copy from the stdio buffer to the mhl input buffer, then
> write() results in a copy from the mhl input buffer to the kernel, and then
> there is a copy from the kernel to replyfilter's input (not sure if that's
> using stdio there).  So that's at least 4 copies.  I tested replyfilter out
> with files in the tens of megabytes and I didn't notice any delay (the
> bulk of the messages were attachments that replyfilter didn't output, but
> it still had to read the whole message).  So yeah, that would have bogged
> down 20 years ago, but not today.

Perhaps the optimization needed here isn't in the buffer copies, per se :-)

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