From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Emilio G. Cota" <cota@braap.org>
Subject: Re: [PATCH v3 2/5] util: introduce threaded workqueue
Date: Mon, 26 Nov 2018 13:55:04 -0500
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Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com,
	Xiao Guangrong <xiaoguangrong@tencent.com>,
	qemu-devel@nongnu.org, peterx@redhat.com,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	quintela@redhat.com, wei.w.wang@intel.com,
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To: Xiao Guangrong <guangrong.xiao@gmail.com>
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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.

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.

Thanks,

		Emilio