Messages in this thread | | | Date | Thu, 26 Sep 2013 17:42:52 -0400 | From | Peter Hurley <> | Subject | Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data" |
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On 09/26/2013 02:05 PM, Andrew Morton wrote: > On Thu, 26 Sep 2013 13:35:32 -0400 Peter Hurley <peter@hurleysoftware.com> wrote: > >> The issue with a single large kmalloc is that it may fail where >> 3 separate, page-or-less kmallocs would not have. > > Or vmalloc fails first, because of internal fragmentation of the vmap > arena. This problem plus vmalloc's slowness are the reasons why > vmalloc should be avoided.
Ok, no vmalloc.
> A tremendous number of places in the kernel perform higher-order > allocations nowadays. The page allocator works damn hard to service > them and I expect that switching to kmalloc here will be OK.
I've had order-4 allocation failures before on 10Gb. In fact, the nouveau driver switched to vmalloc for that very reason (commit d005f51eb93d71cd40ebd11dd377453fa8c8a42a, drm/nouveau: use vmalloc for pgt allocation).
Regards, Peter Hurley
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