From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Nigel Roles" To: <9fans@cse.psu.edu> Subject: RE: [9fans] Threads: Sewing badges of honor onto a Kernel Message-ID: <000d01c3fddf$72cc45b0$2bdcfea9@blue> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit In-Reply-To: <20040228105025.1a94f714.martin@parvat.com> Date: Sat, 28 Feb 2004 09:44:24 +0000 Topicbox-Message-UUID: 0199af12-eacd-11e9-9e20-41e7f4b1d025 9fans-admin@cse.psu.edu wrote: > If I understand right, I could summarise (one of) Linus's arguments, > as follows: > > The cost of sharing some of VM, but not all (in terms of peformance, > due to less-visible things like TLB flushes, etc), out-weighs having > to write a little bit of assembler wrapping the clone system call > (which only has to be got right once, however horrible it might be). > > I haven't seen any argument rebutting this in any way. If it is true, > then surely a performance hit on all (forked?) processes, is more > important than having to shim a system call? If it is not true, then > it would be nice to know! > > Tell me where I'm wrong, please? > The performance argument may well still be regarded by Linus as stronger, but there are other differences. One is that the stack used by the clone, being allocated on the heap, is fixed in size, and unprotected from overflow.