Messages in this thread | | | Date | Thu, 5 Feb 2015 22:45:00 +1100 | From | Dave Chinner <> | Subject | Re: [PATCH] gfs2: use __vmalloc GFP_NOFS for fs-related allocations. |
| |
On Wed, Feb 04, 2015 at 02:13:29AM -0500, Oleg Drokin wrote: > Hello! > > On Feb 3, 2015, at 5:33 PM, Dave Chinner wrote: > >> I also wonder if vmalloc is still very slow? That was the case some > >> time ago when I noticed a problem in directory access times in gfs2, > >> which made us change to use kmalloc with a vmalloc fallback in the > >> first place, > > Another of the "myths" about vmalloc. The speed and scalability of > > vmap/vmalloc is a long solved problem - Nick Piggin fixed the worst > > of those problems 5-6 years ago - see the rewrite from 2008 that > > started with commit db64fe0 ("mm: rewrite vmap layer").... > > This actually might be less true than one would hope. At least somewhat > recent studies by LLNL (https://jira.hpdd.intel.com/browse/LU-4008) > show that there's huge contention on vmlist_lock, so if you have vmalloc
vmlist_lock and the list it protected went away in 3.10.
Cheers,
Dave. -- Dave Chinner david@fromorbit.com
| |