Messages in this thread |  | | | Date | Thu, 2 Apr 2009 09:53:31 -0400 (EDT) | | From | Christoph Lameter <> | | Subject | Re: [PATCH UPDATED] percpu: use dynamic percpu allocator as the default percpu allocator |
| |
On Thu, 2 Apr 2009, Ingo Molnar wrote:
> to quote an earlier part of my mail: > > > > We encourage kfree(NULL) and it triggers commonly in the kernel > > > today [on distro kernels we checked it can trigger once per > > > syscall!] - so i think we should consider free_percpu(NULL) a > > > possibly common pattern too. (even though today it's likely > > > _not_ common at all.) > > I specifically mentioned that it is not at all common now.
What is this? Nonsense day? Consider it a common pattern although its likely not common at all? April fools day?
> But there's no reason why an object shutdown fastpath with an > optional percpu buffer (say for debug statistics, not enabled by > default) couldnt look like this: > > percpu_free(NULL); > > We actually have such patterns of kfree(ptr) use, where the _common_ > case in a fastpath is kfree(NULL).
Speculation. A shutdown fastpath? The percpu allocation and free operations are expensive and deal with teardown and setup of virtual mappings. Those paths are *not* optimized for fastpath use. kfree is different.
|  |