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RE: [Xen-devel] [patch] new version of find_domain_by_id() without reference count [0/6]


> -----Original Message-----
> From: Keir Fraser [mailto:keir@xxxxxxxxxxxxx] 
> Sent: Saturday, December 09, 2006 1:29 AM
> To: Santos, Jose Renato G; xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Turner, Yoshio; G John Janakiraman
> Subject: Re: [Xen-devel] [patch] new version of 
> find_domain_by_id() without reference count [0/6]
> On 9/12/06 4:09 am, "Santos, Jose Renato G" <joserenato.santos@xxxxxx>
> wrote:
> > I only did minor tests on x86-32. Xen and dom0 boots fine and I can 
> > create and destroy domains. But, no more exaustive tests 
> were done. I 
> > carefully checked if I removed all put_domain() associated 
> with each 
> > modified invocation of find_domain_by_id but mistakes are always 
> > possible. It would be good to put this to some more 
> exhaustive tests 
> > before pushing it to the main tree. Waiting for post 3.0.4 
> release is 
> > strongly suggested.
> It can't go in until RCU is merged and that won't happen for 
> 3.0.4 anyway.
> When you post these again after 3.0.4 (which I'm sure you'll 
> have to do) I'd actually like the names as follows:
>  1. Rename find_domain_by_id() to get_domain_by_id().
>  2. Call the new function find_domain_by_id().
> This has the obvious disadvantage of an old/new name clash so 
> we effectively change semantics of an existing function. 
> *But* the new names are better
> imo: get_domain_by_id() more obviously pairs with put_domain(), and
> find_domain_by_id_noref() is ugly and this rename allows us 
> to drop the _noref suffix unambiguously.

  Yes, I also thought we needed better names but my thinking was that
  we could change the names in separate patches after we were sure
  no code was still using find_domain_by_id() with the old semantics.
  Since I can only run and compile the x86 version I was afraid that
  I might have missed some code using find_domain_by_id() in the
  other archs. But I guess I was being too conservative. It is 
  probably fine to change the names as you suggested in the next

> I'd be interested to know what this does for 
> find/get_domain_by_id() percentages in your network profiles.

  For TCP TX find_domain_by_id() cost is reduced from 3.05% of the
  total CPU cycles to 0.19% in my machine using the new version. 
  I have not run a RX benchmark yet, but I can get those numbers



>  -- Keir

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