On Mon, 2007-05-14 at 12:56 -0700, Christoph Lameter wrote: > On Mon, 14 May 2007, Peter Zijlstra wrote: > > > > You can pull the big switch (only on a SLUB slab I fear) to switch > > > off the fast path. Do SetSlabDebug() when allocating a precious > > > allocation that should not be gobbled up by lower level processes. > > > Then you can do whatever you want in the __slab_alloc debug section and > > > we > > > wont care because its not the hot path. > > > > One allocator is all I need; it would just be grand if all could be > > supported. > > > > So what you suggest is not placing the 'emergency' slab into the regular > > place so that normal allocations will not be able to find it. Then if an > > emergency allocation cannot be satified by the regular path, we fall > > back to the slow path and find the emergency slab. > > Hmmm.. Maybe we could do that.... But what I had in mind was simply to > set a page flag (DebugSlab()) if you know in alloc_slab that the slab > should be only used for emergency allocation. If DebugSlab is set then the > fastpath will not be called. You can trap all allocation attempts and > insert whatever fancy logic you want in the debug path since its not > performance critical.
I might have missed some detail when I looked at SLUB, but I did not see how setting SlabDebug would trap subsequent allocations to that slab. > > The thing is; I'm not needing any speed, as long as the machine stay > > alive I'm good. However others are planing to build a full reserve based > > allocator to properly fix the places that now use __GFP_NOFAIL and > > situation such as in add_to_swap(). > > Well I have version of SLUB here that allows you do redirect the alloc > calls at will. Adds a kmem_cache_ops structure and in the kmem_cache_ops > structure you can redirect allocation and freeing of slabs (not objects!) > at will. Would that help? I'm not sure; I need kmalloc as well. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
