RE: [Xen-devel] [PATCH] Add RCU support into Xen - Repost

["Santos, Jose Renato G" <joserenato.santos@xxxxxx>]

> -----Original Message-----
> From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] 
> Sent: Friday, January 26, 2007 10:40 AM
> To: Santos, Jose Renato G; xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Turner, Yoshio; Jose Renato Santos; G John Janakiraman
> Subject: Re: [Xen-devel] [PATCH] Add RCU support into Xen - Repost
> 
> On 17/1/07 12:36 am, "Santos, Jose Renato G" 
> <joserenato.santos@xxxxxx>
> wrote:
> 
> >   I am planning to submit the following additional patches, 
> after this 
> > one is accepted:
> 
> Now done. C/s 13648. I ripped out a few more bits of the 
> Linux RCU implementation and moved the hooks in schedule.c to 
> a single hook in do_softirq(). I suspect there is a tradeoff 
> between timeliness of checking for pending work and building 
> up nice batches of RCU work but checking in
> do_softirq() shouldn't mean we're hitting the RCU variables too often.
> 

  Yes, that should be fine. The overhead should be small if we are only
  checking if there is RCU work to do.

  Looking at your changes, I think there are a few more bits that we can
  remove of the Linux RCU implementation. I will prepare a patch
  for you with some cleanup later. But, for now I would like to focus
  on the patches that modify the domain list manipulation and
  find_domain_by_id()to use the new RCU functions.

  While doing that I noticed that you removed the definitions of
  "rcu_read_lock()" and "rcu_read_unlock()" from rcupdate.h.
  Although they are really NOPs I think it would be good if we use
  them in all RCU read critical sections, for code clarity
  and documentation (as linux does).
  Can we add those back?

  Thanks

  Renato

> >     1) rename_find_domain.patch: Rename find_domain_by_id() to
> > get_domain_by_id()
> 
> Also done, by sed. C/s 13649.
> 
>  -- Keir
> 
> >     2) add_find_domain.patch: Add new find_domain_by_id() function 
> > that uses RCU
> >     3) use_find_domain.patch: Replace invocations of
> > get_domain_by_id()/put_domain() by find_domain_by_id() 
> where possible.
> 
> 
> 

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