lkml.org 
[lkml]   [2012]   [Jan]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush
On 01/01/2012 06:12 PM, Gilad Ben-Yossef wrote:
> >
> > Since this seems to be a common pattern, how about:
> >
> > zalloc_cpumask_var_or_all_online_cpus(&cpus, GFTP_ATOMIC);
> > ...
> > free_cpumask_var(cpus);
> >
> > The long-named function at the top of the block either returns a newly
> > allocated zeroed cpumask, or a static cpumask with all online cpus set.
> > The code in the middle is only allowed to set bits in the cpumask
> > (should be the common usage). free_cpumask_var() needs to check whether
> > the freed object is the static variable.
>
> Thanks for the feedback and advice! I totally agree the repeating
> pattern needs abstracting.
>
> I ended up chosing to try a different abstraction though - basically a wrapper
> on_each_cpu_cond that gets a predicate function to run per CPU to
> build the mask
> to send the IPI to. It seems cleaner to me not having to mess with
> free_cpumask_var
> and it abstracts more of the general pattern.
>

This converts the algorithm to O(NR_CPUS) from a potentially lower
complexity algorithm. Also, the existing algorithm may not like to be
driven by cpu number. Both are true for kvm.

--
error compiling committee.c: too many arguments to function



\
 
 \ /
  Last update: 2012-01-01 17:53    [W:0.113 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site