Re: increased vmap_area_lock contentions on"n_tty: Move buffers into n_tty_data"

From: Andrew Morton
Date: Thu Sep 26 2013 - 14:05:45 EST

On Thu, 26 Sep 2013 13:35:32 -0400 Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> 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.

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.
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