[PATCH] makedumpfile: reverse -c and -p if using snappy compression

[Maxim Uvarov]

2013/9/10 Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp>:
> Hello Maxim,
>
>
> (2013/08/30 18:52), Maxim Uvarov wrote:
>>
>> I think that better is to have:
>>
>> -cz zlib
>> -cs snappy
>> -cl zlo
>
>
> They are main options for most users, so I don't want to change
> them without any important reason.
>
>
>> -ca - automatic selection of compression. Snappy if compiled in, then
>> lzo. And if no snappy and lzo then zlib.
>
>
> What is the selection standard ? Compression Speed ?
> If some users prefer compression ratio to compression speed,
> snappy isn't suitable for them.
>
> Each compression format has both good points and bad points,
> so

>each user should select the format manually based on the
> purpose in any case.
>

That definitely does not work in real life. Nobody wants to set up
something, read manual and understand all options.  More than that -
if  you somehow updated configs and set up wrong option you will not
receive any dump instead of receiving dump with different compression.

BR,
Maxim.
>
> Thanks
> Atsushi Kumagai
>
>
>> this will make options more readable.
>>
>> Best regards.
>> Maxim.
>>
>>
>> 2013/8/30 Baoquan He <bhe at redhat.com>:
>>>
>>> USESNAPPY is a switch which the snappy support has been built into.
>>> With this flag, it means snappy compression algorithm is available.
>>> Which compression algorithm is taken need be decided by -c/-l/-p.
>>>
>>> If I make a build with USELZO and USESNAPPY, then I want to test
>>> zlib/lzo/snappy separately, then this patch will confuse me very
>>> much. Current action and configuration are enough for me. So it's
>>> better to leave the current action alone.
>>>
>>> Baoquan
>>> Thanks
>>>
>>> On 08/28/13 at 05:08pm, Cliff Wickman wrote:
>>>>
>>>> From: Cliff Wickman <cpw at sgi.com>
>>>>
>>>> Reverse the meanings of -c (compression) and -p (snappy compression) if
>>>> USESNAPPY is defined.
>>>>
>>>> The distro kdump scripts seem to only support -c for compression.
>>>> So make -c mean snappy compression if it is supported.
>>>>
>>>> Diffed against makedumpfile-1.5.4
>>>> Signed-off-by: Cliff Wickman <cpw at sgi.com>
>>>> ---
>>>>   makedumpfile.c |   10 ++++++++++
>>>>   print_info.c   |   13 +++++++++----
>>>>   2 files changed, 19 insertions(+), 4 deletions(-)
>>>>
>>>> Index: makedumpfile-1.5.4/makedumpfile.c
>>>> ===================================================================
>>>> --- makedumpfile-1.5.4.orig/makedumpfile.c
>>>> +++ makedumpfile-1.5.4/makedumpfile.c
>>>> @@ -8607,7 +8607,12 @@ main(int argc, char *argv[])
>>>>                        info->name_filterconfig = optarg;
>>>>                        break;
>>>>                case 'c':
>>>> +#ifdef USESNAPPY
>>>> +                     /* if snappy is available make it the default */
>>>> +                     info->flag_compress = DUMP_DH_COMPRESSED_SNAPPY;
>>>> +#else
>>>>                        info->flag_compress = DUMP_DH_COMPRESSED_ZLIB;
>>>> +#endif
>>>>                        break;
>>>>                case 'D':
>>>>                        flag_debug = TRUE;
>>>> @@ -8656,7 +8661,12 @@ main(int argc, char *argv[])
>>>>                        info->flag_dmesg = 1;
>>>>                        break;
>>>>                case 'p':
>>>> +#ifdef USESNAPPY
>>>> +                     /* is snappy is available only use zlib with -p */
>>>> +                     info->flag_compress = DUMP_DH_COMPRESSED_ZLIB;
>>>> +#else
>>>>                        info->flag_compress = DUMP_DH_COMPRESSED_SNAPPY;
>>>> +#endif
>>>>                        break;
>>>>                case 'P':
>>>>                        info->xen_phys_start = strtoul(optarg, NULL, 0);
>>>> Index: makedumpfile-1.5.4/print_info.c
>>>> ===================================================================
>>>> --- makedumpfile-1.5.4.orig/print_info.c
>>>> +++ makedumpfile-1.5.4/print_info.c
>>>> @@ -41,9 +41,9 @@ print_usage(void)
>>>>   #endif
>>>>        MSG("snappy support:\n");
>>>>   #ifdef USESNAPPY
>>>> -     MSG("  enabled\n");
>>>> +     MSG("  enabled using -c\n");
>>>>   #else
>>>> -     MSG("  disabled ('-p' option will be ignored.)\n");
>>>> +     MSG("  disabled\n");
>>>>   #endif
>>>>        MSG("\n");
>>>>        MSG("Usage:\n");
>>>> @@ -90,8 +90,13 @@ print_usage(void)
>>>>        MSG("\n");
>>>>        MSG("Available options:\n");
>>>>        MSG("  [-c|-l|-p]:\n");
>>>> -     MSG("      Compress dump data by each page using zlib for -c
>>>> option, lzo for -l option\n");
>>>> -     MSG("      or snappy for -p option. A user cannot specify either
>>>> of these options with\n");
>>>> +#ifdef USESNAPPY
>>>> +     MSG("      Compress dump data by each page using zlib for -p
>>>> option, lzo for -l option\n");
>>>> +     MSG("      or snappy for -c option. A user cannot specify any of
>>>> these options with\n");
>>>> +#else
>>>> +     MSG("      Compress dump data by each page using zlib for -c
>>>> option or lzo for -l option\n");
>>>> +     MSG("      A user cannot specify either of these options with\n");
>>>> +#endif
>>>>        MSG("      -E option, because the ELF format does not support
>>>> compressed data.\n");
>>>>        MSG("      THIS IS ONLY FOR THE CRASH UTILITY.\n");
>>>>        MSG("\n");
>>>>
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>>>
>>>
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>>
>>
>>
>>
>



-- 
Best regards,
Maxim Uvarov