I think this probably belongs in the book, but I don't know exactly where...so I'll ensure that it's noted again and let someone else figure out where it should live.
As we start to have more users with ra_serf, we should also recommend that httpd server admins bump up their MaxKeepAliveRequests from 100 (default) to at least 1000. This'll help ra_serf utilize TCP connections more efficiently - as ra_serf issues 2 HTTP requests per file that it needs to check out or update. ra_serf has heuristics so that it'll work gracefully under the default settings (and determine what the value actually is), but you'll get better network performance if you can utilize fewer TCP connections. This way, ra_serf will only need to open a new connection every 500 files rather than every 50. (Honestly, there is really no reason that it couldn't be 10000.) If we also have a tuning section, we should remind folks to also enable mod_deflate (SetOutputFilter DEFLATE in their Location block) as that'll help a bit when transferring XML content back and forth. mod_deflate will come at a slight latency penalty, but that'll be offset for folks with slower connections taking less time to transfer the responses overall. FWIW, I've already asked ASF infra to bump up the MaxKeepAliveRequests settings for svn.apache.org. Thanks! -- justin
