Hello HATAYAMA-san,

On Tue, 03 Jul 2012 12:07:27 +0900
HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:

> This patch series add snappy compression support, applied on top of
> v1.4.4. snappy is fast compressoin algorhythm like lzo, but it's more
> optimized than lzo on x86 machines and some others.
>
> A lot of benchmark is available on the web. Here I only point at my
> benchmark I posted a few weeks ago,
>
> - http://lists.infradead.org/pipermail/kexec/2012-June/006425.html
>
> where snappy shows mostly as good performance as simple copying on
> the worst case that input data increases its data size during
> compression; this means we can use snappy with mostly NO risk.
>
> How to get snappy libraries:
>
> 1) Use yum framework to get snappy and snappy-devel packages, or
>
> 2) Visit official website: http://code.google.com/p/snappy/,
> download snappy-<version>.tar.gz and then build it.
>
> How to build makedumpfile with snappy support:
>
> Do make as follows:
>
> $ make USESNAPPY=on

Thank you for your work.

I will merge your patches into the next version with small addition:

diff --git a/README b/README
index ae986d1..638b111 100644
--- a/README
+++ b/README
@@ -45,6 +45,9 @@
6.Build with lzo support:
# make USELZO=on ; make install
The user has to prepare lzo library.
+ 7.Build with snappy support:
+ # make USESNAPPY=on ; make install
+ The user has to prepare snappy library.

* SUPPORTED KERNELS
This makedumpfile supports the following kernels.


In addition, I did brief performance test with your patches:
- The source data is a vmcore saved on the disk, it might be sparse data.
- makedumpfile writes dumpfile to the same disk as the source data.
- execution time is average of 5 times.

| source | zlib | LZO | snappy
------------------------+---------------+-------------+-------------+-------------
size (byte) | 5,107,498,116 | 242,398,239 | 309,549,499 | 487,542,710
compression ratio(%) | --- | 4.75 | 6.06 | 9.55
execution time (sec) | --- | 143 | 49.6 | 51.2


It seems that LZO still has worth in the case that good compression ratio is expected,
as you said in your benchmark report.


Thanks
Atsushi Kumagai

> ---
>
> HATAYAMA Daisuke (8):
> Add manual description
> Add help message
> Add uncompression processing
> Add compression processing
> Notify snappy unsupporting when disabled
> Add snappy build support
> Add command-line processing for snappy
> Add dump header for snappy
>
>
> Makefile | 5 +++++
> diskdump_mod.h | 2 ++
> makedumpfile.8 | 9 +++++---
> makedumpfile.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++------
> makedumpfile.h | 3 +++
> print_info.c | 16 ++++++++++-----
> 6 files changed, 80 insertions(+), 15 deletions(-)
>
> --
>
> Thanks.
> HATAYAMA, Daisuke

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