Re: sablevm.processor.affinity patch

On Wed, 2004-11-17 at 21:14, Chris Pickett wrote:
> Here is my initial crack at support for processor affinity in SableVM. 

Thanks Chris, this looks fairly good.  Some remarks:

- all this stuff has to use #ifdef __linux__ around C code

- on your test system (SMP Gentoo Linux?), does the normal
sched_setaffinity() call work or not?  What is its version of glibc?

- if you need to directly use the syscall() you should have
#ifdef __NR_sched_setaffinity or maybe rather traditional
#ifdef SYS_sched_setaffinity.  Otherwise the compilation would fail
on systems that do not have it defined.

- I think that for now, until SMP issues get fixed, we should use
sysconf() to detect no. of CPUs and if it's bigger than 1 try to set
affinity to a randomly choosen CPU.  There should be an informative
message about it happening outputted while this workaround for SMP
problems is activated.

- looks like the vm->vprintf is assigned fairly early in
JNI_CreateJavaVM, so you should be able to use _svmf_printf() for
printing out any messages (and IMO they should go to stderr, as they're
not part of normal program output).


I am not convinced we really need a configure option for all that. 
Checking whether SYS_sched_affinity is defined should be enough to
ensure that sched_setaffinity() call exists at all.  And calling
syscall() (on Linux) in the worst case will fail which is non-critical
failure.  Thus where possible - we can compile this code in, where not
- we'll automatically disable it using #ifdefs.

Chris, can you prepare an updated patch?

Comments?

			GBP

-- 
Grzegorz B. Prokopski           <[email protected]>
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