Messages in this thread |  | | From | David Howells <> | Subject | Has slab ctor operation changed? -- was [PATCH 1/1] afs: afs_alloc_inode: use kmem_cache_zalloc | Date | Thu, 20 Feb 2014 22:23:15 +0000 |
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Fabian Frederick <fabf@skynet.be> wrote:
> afs_vnode is currently cleared with 2 memsets after allocation and > 1 in constructor (afs_i_init_once). > -This patch calls zalloc for explicit zero fill.
Ummm... This patch isn't necessarily correct in the substantiative portions.
Since afs_i_init_once() is called by the slab allocator during the course of kmem_cache_alloc(), how does kmem_cache_zalloc() interact with that?
IIRC, it used to be that the ctor() function was called when the pages were allocated to the slab - and it wasn't called again, even if the object was allocated, deallocated and reallocated. This means that things like locks and lists don't need reinitialising after allocation.
So afs_i_init_once() theoretically constructs the stuff that can be reused, and afs_alloc_inode() therefore has to clear the non-reusable state.
Of course, it's possible that the slab allocator no longer works like this...
David
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