From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from tyo201.gate.nec.co.jp ([202.32.8.193]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VJIQN-0003ML-GQ for kexec@lists.infradead.org; Tue, 10 Sep 2013 07:31:49 +0000 Message-ID: <522ECA53.1060607@mxc.nes.nec.co.jp> Date: Tue, 10 Sep 2013 16:29:23 +0900 From: Atsushi Kumagai MIME-Version: 1.0 Subject: Re: [PATCH] makedumpfile: reverse -c and -p if using snappy compression References: <20130829025837.GA2298@dhcp12-158.nay.redhat.com> <20130829184652.GA17137@sgi.com> <20130830103337.GA6405@dhcp12-158.nay.redhat.com> In-Reply-To: <20130830103337.GA6405@dhcp12-158.nay.redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: chaowang@redhat.com Cc: d.hatayama@jp.fujitsu.com, kexec@lists.infradead.org, cpw@sgi.com (2013/08/30 19:33), WANG Chao wrote: > On 08/29/13 at 01:46pm, Cliff Wickman wrote: >> On Thu, Aug 29, 2013 at 10:58:37AM +0800, WANG Chao wrote: >>> Hi, Cliff >>> >>> On 08/28/13 at 05:08pm, Cliff Wickman wrote: >>>> From: Cliff Wickman >>>> >>>> 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. >>> >>> It looks like more a distro issue to me. I'm wondering if that script >>> only support -c, why do that distro compile makedumpfile with USESNAPPY? >>> >>> I don't think other distros would like to see this change. IMHO, the >>> right thing to do is fix that kdump script on that particular distro, >>> not reverse -c and -p. >>> >>> Thanks >>> WANG Chao >> >> I agree that some distros could easily change their default compression >> choice, for example -c to -p in RHEL's /etc/kdump.conf. >> >> But on the other hand SLES11 just uses KDUMP_DUMPFORMAT="compressed" >> in /etc/sysconfig/kdump. Translation to -c occurs somewhere under the >> covers. > > Instead, it's reasonable to patch SLES11 kdump utility, not upstream. Yes, it should be resolved in distro side. > -c means using zlib and -p means using snappy. That's already established > and has been widely used. > >> Makedumpfile could change the default meaning of "compressed" to snappy >> compression on the grounds that we know snappy to be much faster than >> zlib compression. And so we default to it if available. > > IMO, makedumpfile doesn't have default compression format. c/p/l means > zlib/snappy/lzo by each. If you don't specify one of them, makedumpfile > wouldn't do compression work. > > You could assume -c means default compression format, but I see it means > compress with zlib. I agree to WANG. -c just means to compress with zlib. There is no mention of default format also in the man page. -c,-l,-p Compress dump data by each page using zlib for -c option, lzo for -l option or snappy for -p option. (-l option needs USELZO=on and -p option needs USESNAPPY=on when building) Thanks Atsushi Kumagai >> You would in that way make the intelligent choice without administrative >> intervention. > > The intelligent choice can be made within distro specific kdump script > rather than makedumpfile. > >> (You would also have to assume that crash is also be built snappy-capable >> for a system that supports snappy compression.) >> >> I could see it either way. >> I find this patch a convenient way to make the choice. > > This patch could cause regression and break current existing kdump > scripts. I wouldn't worry much about the -c (zlib) user though. > > As for the people using -p to snappy compression, after upgrading their > makedumpfile, they would get zlib format dump if their kdump conf remain > untouched. > > Thanks > WANG Chao > > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec