Luck, Tony
2005-Nov-23 15:07 UTC
RE: [Xen-devel] __ia64__ ifdef in xmalloc.c: "Fix ar.unat handling forfast paths"
>It''s not hard to support arbitrary alignment, at the cost of burning >some space. We should probably do that.The "we" in that last sentence is the Xen team ... referring to making fixes to xmalloc? -Tony _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2005-Nov-23 15:37 UTC
Re: [Xen-devel] __ia64__ ifdef in xmalloc.c: "Fix ar.unat handling forfast paths"
On 23 Nov 2005, at 15:07, Luck, Tony wrote:>> It''s not hard to support arbitrary alignment, at the cost of burning >> some space. We should probably do that. > > The "we" in that last sentence is the Xen team ... referring > to making fixes to xmalloc?Correct. But I''ve thought more on it and I guess that actually the number of cases where we have structures with alignment requirements stricter than SMP_CACHE_BYTES will be very small. In fact I can''t think of any in Xen right now. :-) So it makes most sense for ia64 Xen to define SMP_CACHE_BYTES to a sensible largeish number irrespective of CONFIG_SMP (after all, how many uniproc ia64 systems are there), and solve the general alignment problem in xmalloc only if we really need to. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Rusty Russell
2005-Nov-23 23:22 UTC
Re: [Xen-devel] __ia64__ ifdef in xmalloc.c: "Fix ar.unat handling forfast paths"
On Wed, 2005-11-23 at 15:37 +0000, Keir Fraser wrote:> On 23 Nov 2005, at 15:07, Luck, Tony wrote: > > >> It''s not hard to support arbitrary alignment, at the cost of burning > >> some space. We should probably do that. > > > > The "we" in that last sentence is the Xen team ... referring > > to making fixes to xmalloc? > > Correct. But I''ve thought more on it and I guess that actually the > number of cases where we have structures with alignment requirements > stricter than SMP_CACHE_BYTES will be very small. In fact I can''t think > of any in Xen right now. :-)Right, which was why the original BUG_ON() which started this discussion... Rusty. -- A bad analogy is like a leaky screwdriver -- Richard Braakman _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel