The master process exec's the mail process (imap or pop3) after fork. gpg
2008/8/15 Sebastien Tandel <[EMAIL PROTECTED]>: > Hi, > > >>> It is well known that preforking is a good pratice if you want to >>> achieve a higher performance. >>> When I was asked about it I readily answered: "of course it does". For >>> my surprise later, i doesn't. >> >> With fork latencies in the range of 500 to 1500 microseconds (on Pentium >> 900 MHz-class hardware!) on most modern kernels[1] I wonder whether this >> "good practice" isn't on the verge of voodoo ;-) > > OK, it measures the fork instruction. But fork is using a copy-on-write > mechanism ... It means that *none* of the parent's memory pages are copied. > Each page is simply *shared* by *all* the child /until/ a modification is > made to it.Therefore this test obviously does not take into account time > taken when modifying data. And I strongly suspect that dovecot is not only > doing read-only access to memory when running. :-/ > > P.S. : I'm not saying though it is mandatory to have such a mechanism in > dovecot ;) > > > Regards, > Sebastien > >> (Of course, in a http server, where you might expect thousands of >> connects per second, this is another story -- which is mitigated by HTTP >> 1.1, when properly streaming several requests per connection). >> >> - ---------------- >> [1] <http://bulk.fefe.de/scalability/>, search "The fork benchmark" >> >> Regards >> - -- tomás >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1.4.6 (GNU/Linux) >> >> iD8DBQFIpR1XBcgs9XrR2kYRAqPdAJ0dbp+fUW0MpWdNvXa3SUvXP3v3eQCcCsTS >> hFbhMpoG+OjI4i+za6xNn+4= >> =SRgx >> -----END PGP SIGNATURE----- >> > >
