Re: [2/2] vmallocinfo: Add caller information

From: Christoph Lameter
Date: Tue Apr 29 2008 - 15:10:37 EST


On Mon, 28 Apr 2008, Arjan van de Ven wrote:

> > Hmmm... Why do we have CONFIG_FRAMEPOINTER then?
>
> to make the backtraces more accurate.

Well so we display out of whack backtraces? There are also issues on
platforms that do not have a stack in the classic sense (rotating register
file on IA64 and Sparc64 f.e.). Determining a backtrace can be very
expensive.

> > The current implementation of vmalloc_caller() follows what we have
> > done with kmalloc_track_caller. Its low overhead and always on.
>
> stacktraces aren't entirely free, the cost is O(nr of modules) unfortunately ;(

The current implementation /proc/vmallocinfo avoids these issues and
with just one caller address it can print one line per vmalloc request.
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