cvs commit: src/sys/dev/disk/nata ata-all.c
Simon 'corecode' Schubert
corecode at fs.ei.tum.de
Wed Dec 13 16:07:20 PST 2006
Matthew Dillon wrote:
:why do we have to call the ctor and dtor anyways? why not do if (oc->cto=
:r) oc->ctor(obj); ? or am i missing something important there?
:
:cheers
: simon
I was operating under the assumption that the objcache would normally
have a ctor / dtor function, so I didn't want to add another conditional
to that path. This isn't entirely true any more... or rather, only
the mbuf subsystem really uses the feature.
Ok, I AM a bit on the fence here. I know that implementing M_ZERO adds
one conditional to the hot path, but the M_ flags (like M_NOWAIT) are
kinda integral to the allocation subsystem and I don't want to throw
one away just to save a few nanoseconds.
I agree. M_NOWAIT is important to obey, but that's also no problem. I think we can safely assume that all consumers of object cache functions do know what they want and simply disallow M_ZERO. That's no big deal, because we don't have any of such consumers anyways. The whole concept of an object cache collides with using M_ZERO. Really, if you want to zero out data, use bzero. IIRC, M_ZERO also just optimizes page-sized allocations with kmalloc(), even if. Everybody who is using objects should be using them the right way, which implies not using M_ZERO.
cheers
simon
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