On Fri, May 01, 2015 at 08:18:56PM +0000, Simmons, James A. wrote: > >> >From: Julia Lawall <Julia.Lawall@xxxxxxx> > >> > > >> >Replace OBD_ALLOC, OBD_ALLOC_WAIT, OBD_ALLOC_PTR, and OBD_ALLOC_PTR_WAIT by > >> >kalloc/kcalloc, and OBD_FREE and OBD_FREE_PTR by kfree. > >> > >> Nak: James Simmons <jsimmons@xxxxxxxxxxxxx> > >> > >> A simple replace will not work. The OBD_ALLOC and OBD_FREE functions allocate memory > >> anywhere from one page to 4MB in size. You can't use kmalloc for the 4MB allocations. > >> Currently lustre uses a 4 page water mark to determine if we allocate using vmalloc. Even > >> using kmalloc for 4 pages has shown high failure rates on some systems. It gets even more > >> messy with 64K page systems like ppc64 boxes. Now I'm not suggesting to port the larger > >> allocations to vmalloc either since issues have been founded with using vmalloc. For example > >> when using large stripe count files the MDS rpc generated crosses the 4 page line and vmalloc > >> is used. Using vmalloc caused a global spinlock to be taken which causes meta data operations > >> to serialized on the MDS servers. > > > >It's not the LARGE functions that do the switching? For example OBD_ALLOC > >ends up at __OBD_MALLOC_VERBOSE, which as far as I can see calls kmalloc > >(with __GFP_ZERO, and hance the use of kzalloc). > > Yes the LARGE functions do the switching. I was expecting also patches to remove the > OBD_ALLOC_LARGE functions as well which is not the case here. I do have one question still. The > macro __OBD_MALLOC_VERBOSE allowed the ability to simulate memory allocation failures at > a certain percentage rate. Does something exist in the kernel to duplicate that functionality? Yes, no need for lustre to duplicate yet-another-thing the kernel already provides :) _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
