-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Matt Kettler writes: > At 01:49 PM 10/26/2004, Luis Hernán Otegui wrote: > >What really pisses me off is the fact that in the rest of my servers, > >when SA starts, only the parent process weights 22 MB, the children > >weight approx. 5 MB each. But in this particular server, all of the > >spamd processes start up as 22 MB processes... > > It strikes me as rather odd that the size of them is different. In theory > they should all be the same. > > What kernels are the boxes using? > > One theory I have is that the boxes with 5mb children has a RCU enabled > kernel, thus the children are 5mb of their own memory, and the rest is > shared with the map of the parent. (RCU causes forked children to share > pages of memory with the parent until they modify the page, then it gets > reallocated) > > On the one box which has 22mb children, I suspect there's no RCU support, > so the whole 22mb parent is copied at the time of fork(). > > In linux, RCU is present on 2.6.x kernels, although some vendors may have > backported it to their 2.4x kernels nah, that's Copy-On-Write you're thinking of, which has been std in linux and most UNIX kernels since 2.2.x ;) Every 2.4.x and 2.6.x kernel will do this just fine -- although 2.6.x and Red Hat 2.4.x kernels report their statistics incorrectly, making it seem to *not* be working. I think Luis means that the parent is 22mb, and the children share most of that memory except for 5mb of their own VSZ, which is about right. - --j. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Exmh CVS iD8DBQFBfpSnMJF5cimLx9ARAtbnAKCMREGoWwGCMFtxF/p2E3rTTF/2VACgmaHo qGleOmvPexQ6uCbmgFsflbE= =OKIU -----END PGP SIGNATURE-----
