Re: [Qemu-devel] [PATCH v3 2/5] util: introduce threaded workqueue

[Xiao Guangrong]

On 11/27/18 2:55 AM, Emilio G. Cota wrote:
> On Mon, Nov 26, 2018 at 15:57:25 +0800, Xiao Guangrong wrote:
> > On 11/23/18 7:02 PM, Dr. David Alan Gilbert wrote:
> >
> > > > +#include "qemu/osdep.h"
> > > > +#include "qemu/bitmap.h"
> > > > +#include "qemu/threaded-workqueue.h"
> > > > +
> > > > +#define SMP_CACHE_BYTES 64
> > >
> > > That's architecture dependent isn't it?
> >
> > Yes, it's arch dependent indeed.
> >
> > I just used 64 for simplification and i think it is <= 64 on most CPU arch-es
> > so that can work.
> >
> > Should i introduce statically defined CACHE LINE SIZE for all arch-es? :(
>
> No, at compile-time this is impossible to know.
>
> We do query this info at run-time though (see util/cacheinfo.c),
> but using that info here would complicate things too much.

I see.

> You can just give it a different name, and perhaps add a comment.
> See for instance what we do in qht.c with QHT_BUCKET_ALIGN.

That's really a good lesson to me, will follow it. :)