cvs commit: src/sys/dev/disk/nata ata-all.c

[Simon 'corecode' Schubert]

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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