Re: [Qemu-devel] [PATCH V6 1/6] oslib-posix: add helpers for stack alloc and free

[Peter Lieven]

Am 22.08.2016 um 17:19 schrieb Richard Henderson:
> On 08/22/2016 06:04 AM, Peter Lieven wrote:
> > +static size_t adjust_stack_size(size_t sz)
> > +{
> > +#ifdef _SC_THREAD_STACK_MIN
> > +    /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
> > +    sz = MAX(MAX(sysconf(_SC_THREAD_STACK_MIN), 0), sz);
> > +#endif
>
> You need to place the sysconf result into a local variable.  What you have now 
> expands to 4 invocations of the function.

okay, I thought it would only be 2 calls and its not critical. but I can change 
that.

> You might also consider passing in the pagesize, since you've already called 
> getpagesize in one of the two users of this function.

I can change this as well, but isn't getpagesize just a macro on most systems?
If the call of getpagesize is critical we should cache it somewhere as there 
are more critical sections that call it repeatly.

Peter