Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables

From	Minfei Huang <mnghuan@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables
Date	2016-05-11 17:30 +0200
Message-ID	<rxEfg-2vs-15@gated-at.bofh.it> (permalink)
References	(1 earlier) <rtD85-4Q-1@gated-at.bofh.it> <rtHbI-384-15@gated-at.bofh.it> <rtIAO-4s0-17@gated-at.bofh.it> <rtL5H-6vQ-37@gated-at.bofh.it> <rxDjc-1to-35@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 05/11/16 at 04:24P, Paolo Bonzini wrote:
> 
> 
> On 30/04/2016 23:57, Andy Lutomirski wrote:
> >> > Should we kill __pvclock_read_cycles in favor of vread_pvclock? It looks
> >> > doable at a quick scan...
> >> >
> > The in-kernel version might have to be a bit different because it
> > needs to handle the !stable case.  If !stable, it should just use the
> > current CPU's copy which means that, realistically, it should just
> > get_cpu and use the local copy unconditionally.  Other than that, it
> > could look a lot like the vread_pvclock variant.
> > 
> > But I agree, the current thing is incomprehensible.
> 
> It also lacks smp_rmb()s.  One is more or less implicit in rdtsc, but
> you need one to separate __pvclock_read_cycles's reads of src->foo from
> pvclock_read_flags's read of src->version.
> 
> Minfei, would you like to take a look?

Sure. I will take a look about this issue.

Thanks
Minfei

> 
> Paolo

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Borislav Petkov <bp@suse.de> - 2016-04-30 15:30 +0200
  Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Andy Lutomirski <luto@amacapital.net> - 2016-04-30 19:50 +0200
    Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Borislav Petkov <bp@suse.de> - 2016-04-30 21:20 +0200
      Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Andy Lutomirski <luto@amacapital.net> - 2016-05-01 00:00 +0200
        Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Paolo Bonzini <pbonzini@redhat.com> - 2016-05-11 16:30 +0200
          Re: [PATCH] Cleanup __pvclock_read_cycles to remove useless variables Minfei Huang <mnghuan@gmail.com> - 2016-05-11 17:30 +0200

csiph-web