On Apr 30 01:58, Charles Wilson wrote: > antony baxter wrote: >>> 1. In all cases, the ftpd process' memory usage increases to ~350mb, >>> 2. As the buffer value decreases, the process' cpu usage increases >>> (ftpd-1k.exe used about 75% of the cpu vs. about 10% for ftpd-8k.exe), >>> 3. Performance jumped around (ftpd-1k transferred the file in >>> 90seconds, ftpd-4k in 166 seconds, ftp-8k in 114 seconds on a wired >>> network) >> Quick addendum: I copied over in.ftpd.exe from another Cygwin >> installation running inetutils 1.3.2 and symlinked it to ftpd on my >> server; using that to serve the same file, memory usage sticks at >> 3500kb, cpu usage never rises about 5%, and the file was delivered in >> 194 seconds. > > Well, one of the differences between ftpd-1.3.2 and ftpd-1.5 is that the > newer version uses mmap on the (local) file. ftpd.c is the /only/ source > file in inetutils that uses mmap.
Ok, so the ftpd using mmap is faster, one way or another. > So, I recompiled with HAVE_MMAP turned off (but still using 4k chunks). > Give this a try: > > http://cygwin.cwilson.fastmail.fm/ITP/ftpd-no-mmap-4k.exe.bz2 > > I get behavior here which is very similar to what I reported for the > 4k-WITH-mmap version: > (1) sane memory profile > (2) topology one, 9-10 Mbps 2-3% cpu > (3) topology two, 14-15 Mbps, 4-6% cpu [*] > > I'm not sure what benefit mmap has in this case -- unless you can exploit > some zero-copy kernel code for transferring data from disk to ethernet > device. But I don't think Windows has anything like that. I certainly don't > *see* any benefit, in my limited testing on this set of hardware. > > If this *does* fix the problem, it may point to an issue with cygwin-1.5's > mmap implementation, or with XP's handling of the underlying > NtCreateSection()...mmap is not supposed to be CPU-intensive. There might be a bug lurking somewhere. Could you create a very simple testcase which basically behaves like ftpd for debugging? Thanks, Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
