[PATCH] makedumpfile: keep dumpfile pages in a cache

Atsushi Kumagai kumagai-atsushi at mxc.nes.nec.co.jp
Sun Sep 2 23:42:33 EDT 2012

Hello Petr,

On Tue, 28 Aug 2012 19:49:49 +0200
Petr Tesarik <ptesarik at suse.cz> wrote:

> Add a simple cache for pages read from the dumpfile.
> This is a big win if we read consecutive data from one page, e.g.
> page descriptors, or even page table entries.
> Note that makedumpfile now always reads a complete page. This was already
> the case with kdump-compressed and sadump formats, but makedumpfile was
> throwing most of the data away. For the kdump-compressed case, we may
> actually save a lot of decompression, too.
> I tried to keep the cache small to minimize memory footprint, but it should
> be big enough to hold all pages to do 4-level paging plus some data. This
> is needed e.g. for vmalloc areas or Xen page frame table data, which are not
> contiguous in physical memory.
> Signed-off-by: Petr Tesarik <ptesarik at suse.cz>

It's interesting to me. I want to know how performance will be improved
with this patch, so do you have speed measurements ?

Atsushi Kumagai

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