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[Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio
From: |
Paul Brook |
Subject: |
[Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio |
Date: |
Tue, 22 Dec 2009 22:58:16 +0000 |
User-agent: |
KMail/1.12.4 (Linux/2.6.32-trunk-amd64; KDE/4.3.4; x86_64; ; ) |
> > Given this is supposed to be portable code, I wonder if we should have
> > atomic ordered memory accessors instead.
> >
> > Paul
>
> Could you clarify please?
>
> The infiniband bits I used as base are very portable,
> I know they build on a ton of platforms. I just stripped
> a couple of infiniband specific assumptions from there.
>
> Do you suggest we use __sync_synchronize?
> Unfortunately this is broken or slow on many platforms.
> I do use it when it seems safe or when we see a platform
> we don't know about.
I mean have a single function that does both the atomic load/store and the
memory barrier. Instead of:
stw_phys(addr, val)
barrier();
We do:
stw_phys_barrier(addr, val).
This avoids issues in the future (multithreaded TCG) where atomic memory
accesses may be nontrivial.
Paul
- [Qemu-devel] [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/08
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/22
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Anthony Liguori, 2009/12/22
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Paul Brook, 2009/12/22
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/22
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio,
Paul Brook <=
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Paul Brook, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Paul Brook, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Paul Brook, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Paul Brook, 2009/12/23
- [Qemu-devel] Re: [PATCH-RFC 0/3] qemu: memory barriers in virtio, Michael S. Tsirkin, 2009/12/23