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From "Bill Stoddard" <b...@wstoddard.com>
Subject Re: AP_MIN_SENDFILE_BYTES
Date Thu, 01 Feb 2001 01:32:35 GMT

>
> > The patch get around this nicely, however at a steep price on Apache for
> > Windows.  We take a 50% performance hit when serving files smaller than
> > AP_MIN_SENDFILE_BYTES because we cannot use apr_sendfile() and reuse the
> > accept socket.  I would like to consider alternate solutions such as:
> >
> > 1. back this patch out entirely and suffer the small packets on the network
> > for the cases above (which are not that common).
>
> It is common.  Take a look at what the Adobe browser plug-in
> requests.  The last time I looked this made a lot of overlapping range
> requests.

But how prevalent is the adobe browser plug-in?  I really don't know.

>
> > 2. Ryan suggests tuning AP_MIN_SENDFILE_BYTES. To what?  500 bytes? The number
> > needs to be much smaller than 8192 where it is set now. Thoughts?
>
> As I said when I committed the change, we need to run tests, and tune the
> number accordingly.  I guessed at 8192, it is likely wrong, and I said
> that when I committed.  I haven't had the time to run any tests.  Feel
> free to run your own.  If nobody runs them, I will run the tests in a few
> weeks, after we go beta.  Arguing over the correct value without running
> tests doesn't really do us any good.  Let's run the tests, and use real
> numbers to get the answers.
>
> > 3. Bypassing this optimizationonly for byterange requests (or perhaps multiple
> > byterange requests)
>
> Again, let's get some numbers, and speak with real numbers and real
> performance.  I really believe this patch is required, we just need to get
> the cut-off right.
>

What are we testing?  Performance of the byterange request?  I am sure the performance difference
will be substantial on Windows (in favor of using sendfile whenever possible), even with byterange
requests. I'll do some testing tomorrow on Windows.  Have any ideas on: how many byte ranges
the
adobe plug-in 'typically' request (1, 2 many)?  How large are the byte ranges?

Bill



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