Messages in this thread | | | Date | Wed, 23 Aug 2000 22:10:50 +0100 (BST) | From | Tigran Aivazian <> | Subject | Re: SCO: "thread creation is about a thousand times faster than |
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On Thu, 24 Aug 2000, Chris Wedgwood wrote:
> If my benching is right he has rather few instructions to make a > clone 1000x faster ;) > > Nobody has defined faster... what if he is talking about metrics > other than thread/lwp creation? How does an application that makes > heavy use of threads scale under linux compared to SCO?
Have you read the original claim? Here it is:
SCO's Juergen Kienhoefer tells us that by mapping clone processes directly onto UnixWare's native threads, huge performance gains can be realised. "Basically thread creation is about a thousand times faster than on native Linux," he said.
so, we are talking about thread creation only. Nobody would dare to even suggest that actually "running" those threads is "faster" - that would be a scheduler issue and not a clone(2) efficiency issue. So, he is mapping clone(2) onto _lwp_create(2) (well, actually not exactly, I can't remember exactly what he does) so the above claim would suggest that _lwp_create(2) (with some default/reasonable flags) is 1000x faster than clone(2) (e.g. do_fork(CLONE_VM|SIGCHLD, regs)). This I believe to be a lie.
I haven't verified this specific fact but I've done a lot of "UW7 vs Linux" micro-benchmarking (i.e. individual system calls) and found that UW7 is generally a lot slower than Linux. The only case to the contrary was the wait(2) system call (but that is a scheduling issue and we even briefly discussed with someone ages ago).
A good example to see how slow is UW7 - try opening million instances of the same file in a loop. And compare that to Linux - you will see (can't remember exactly, but approximately Linux being several thousands times faster (because it finds unused fd in hardware whilst UW7 in a plain software loop).
Regards. Tigran
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