lkml.org 
[lkml]   [2006]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync
On Mon, 20 Nov 2006, Jens Axboe wrote:

> On Mon, Nov 20 2006, Alan Stern wrote:
> > Paul:
> >
> > Here's my version of your patch from yesterday. It's basically the same,
> > but I cleaned up the code in a few places and fixed a bug (the sign of idx
> > in srcu_read_unlock). Also I changed the init routine back to void, since
> > it's no longer an error if the per-cpu allocation fails.
> >
> > More importantly, I added a static initializer and included the fast-path
> > in synchronize_srcu. It's protected by the new symbol
> > SMP__STORE_MB_LOAD_WORKS, which should be defined in arch-specific headers
> > for those architectures where the store-mb-load pattern is safe.
>
> Must we introduce memory allocations in srcu_read_lock()? It makes it
> much harder and nastier for me to use. I'd much prefer a failing
> init_srcu(), seems like a much better API.

Paul agrees with you that allocation failures in init_srcu() should be
passed back to the caller, and I certainly don't mind doing so.

However we can't remove the memory allocation in srcu_read_lock(). That
was the point which started this whole thread: the per-cpu allocation
cannot be done statically, and some users of a static SRCU structure can't
easily call init_srcu() early enough.

Once the allocation succeeds, the overhead in srcu_read_lock() is minimal.

Alan

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-20 20:43    [W:0.584 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site