[PATCH] keep dumpfile pages in a cache.

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@suse.cz>

1 files changed, 26 insertions, 0 deletions

diff --git a/cache.h b/cache.h
new file mode 100644
index 0000000..f37d883
--- /dev/null
+++ b/cache.h
@@ -0,0 +1,26 @@
+/*
+ * cache.h
+ *
+ * Written by: Petr Tesarik <ptesarik@suse.cz>
+ *
+ * Copyright (c) 2012 SUSE LINUX Products GmbH, Nuernberg, Germany.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _CACHE_H
+#define _CACHE_H
+
+void *cache_search(unsigned long long paddr);
+void *cache_alloc(unsigned long long paddr);
+void cache_add(unsigned long long paddr);
+
+#endif	/* _CACHE_H */