On Fri, 1 May 2015, Simmons, James A. wrote: > >From: Julia Lawall <julia.law...@lip6.fr> > > > >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 <jsimm...@infradead.org> > > 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). julia -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
