From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Subject: Re: perf buildid-cache -p question Date: Sat, 21 Oct 2017 01:12:59 +0900 Message-ID: <20171021011259.5d6368a7fd1f54004b6ae1da@kernel.org> References: <8594e11c-9aa1-f600-3f04-eb80058c9abf@linux.vnet.ibm.com> <20171016141222.GC5311@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail.kernel.org ([198.145.29.99]:46390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752635AbdJTQNB (ORCPT ); Fri, 20 Oct 2017 12:13:01 -0400 In-Reply-To: <20171016141222.GC5311@kernel.org> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Arnaldo Carvalho de Melo Cc: Thomas-Mich Richter , "linux-perf-use." , Hendrik Brueckner , Masami Hiramatsu On Mon, 16 Oct 2017 11:12:22 -0300 Arnaldo Carvalho de Melo wrote: > Em Mon, Oct 16, 2017 at 02:24:11PM +0200, Thomas-Mich Richter escreveu: > > Maybe its me misunderstanding the buildid cache completely, but I ran into the following issue: > > > > I can add and remove files using the perf buildid-cache command. For example > > perf buildid-cache -a /usr/bin/tar adds the tar executable to the buildid-cache directory > > .debug/usr/bin/tar > > and creates the subdirectory > > .debug/usr/bin/tar/e54c9946802bbbcb85760ffeb80700a5fd35ebe7/elf file. > > That is correct. > > > Also a symbolic link from the directory > > .debug/.buildid/e5/4c9946802bbbcb85760ffeb80700a5fd35ebe7 --> ../../usr/bin/tar// > > is created. > > > > Command perf buildid-cache -a /usr/bin/tar > > Nope, command 'perf buildid-cache -r /usr/bin/tar' does it: Wait, -r is remove command. > > [root@jouet ~]# ls -la ~/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > [root@jouet ~]# ls -la ~/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea > lrwxrwxrwx. 1 root root 58 Oct 16 10:50 /root/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea -> ../../usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > [root@jouet ~]# > > [root@jouet ~]# perf buildid-cache -r /usr/bin/tar > [root@jouet ~]# ls -la ~/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > ls: cannot access '/root/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea': No such file or directory > [root@jouet ~]# ls -la ~/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea > ls: cannot access '/root/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea': No such file or directory > [root@jouet ~]# > > > removes these entries. > > > > Now when I run ./perf buildid-cache -p /usr/bin > > nothing happens and success is reported: > > When you do '-p' after a '-a' or after a '-r'? From what you wrote > below, that is after you do a '-a /usr/bin/tar', as it is being purged > as well. > > Masami? Yeah, should be. OK, -p and -r is slightly different. That is for handling "versioning" caches. For example, you have a /usr/bin/tar (this is old tar) and its buildid-cache in cache directory by perf buildid-cache -a /usr/bin/tar. And at some point, you will update the /usr/bin/tar (this is new tar). This new tar binary is not same as old one, so if you also do perf buildid-cache -a /usr/bin/tar, it creates another version of buildid cache in cache directory. At this moment, $ perf buildid-cache -r /usr/bin/tar will remove only new tar's buildid cache, but old one remains. On the other hand, $ perf buildid-cache -p /usr/bin/tar will remove all the caches related to /usr/bin/tar from buildid cache. And since the -p is supposed to be used for cleanup, it doesn't return error even if there is no buildid cache remaining. > > > [root@s35lp76 perf]# ./perf buildid-cache -vp /usr/bin/ > > Removing bash /usr/bin/: Ok > > Removing dbus-daemon /usr/bin/: Ok > > Removing ls /usr/bin/: Ok > > Removing readlink /usr/bin/: Ok > > Removing sleep /usr/bin/: Ok > > Removing tar /usr/bin/: Ok > > Removing time /usr/bin/: Ok > > Removing vim /usr/bin/: Ok > > Purging /usr/bin/: Ok Hmm, curious... > > In my test it works as advertised: > > [root@jouet ~]# perf buildid-cache -a /usr/bin/tar > [root@jouet ~]# ls -la ~/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea > lrwxrwxrwx. 1 root root 58 Oct 16 10:56 /root/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea -> ../../usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > [root@jouet ~]# ls -la ~/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > total 424 > drwxr-xr-x. 2 root root 4096 Oct 16 10:56 . > drwxr-xr-x. 3 root root 4096 Oct 16 10:56 .. > -rwxr-xr-x. 2 root root 425032 Jul 19 05:55 elf > -rw-r--r--. 1 root root 0 Oct 16 10:56 probes > [root@jouet ~]# perf buildid-cache -vp /usr/bin/tar > Removing 4c10f253c0cb8459dd846235c0bc18929e4758ea /usr/bin/tar: Ok > Purging /usr/bin/tar: Ok > [root@jouet ~]# ls -la ~/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > ls: cannot access '/root/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea': No such file or directory > [root@jouet ~]# ls -la ~/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea > ls: cannot access '/root/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea': No such file or directory > [root@jouet ~]# > > It was purged. OK. it seems good. > > Now lets try what you did, which is to ask for a path that will match > with multiple binaries: > > [root@jouet ~]# perf buildid-cache -v -a /usr/bin/tar > Adding 4c10f253c0cb8459dd846235c0bc18929e4758ea /usr/bin/tar: Ok > [root@jouet ~]# ls -la ~/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea > lrwxrwxrwx. 1 root root 58 Oct 16 10:58 /root/.debug/.build-id/4c/10f253c0cb8459dd846235c0bc18929e4758ea -> ../../usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > [root@jouet ~]# ls -la ~/.debug/usr/bin/tar/4c10f253c0cb8459dd846235c0bc18929e4758ea > total 424 > drwxr-xr-x. 2 root root 4096 Oct 16 10:58 . > drwxr-xr-x. 3 root root 4096 Oct 16 10:58 .. > -rwxr-xr-x. 2 root root 425032 Jul 19 05:55 elf > -rw-r--r--. 1 root root 0 Oct 16 10:58 probes > [root@jouet ~]# perf buildid-cache -vp /usr/bin > Removing as /usr/bin: FAIL > Purging /usr/bin: FAIL > /usr/bin wasn't in the cache I think -p does only support a file not a path like that. > [root@jouet ~]# perf buildid-cache -vp /usr/bin/ > Removing as /usr/bin/: FAIL > Purging /usr/bin/: FAIL > /usr/bin/ wasn't in the cache > [root@jouet ~]# > > This is when --purge was added: > > commit 8d8c8e4cb3014fcc51f0e127b4316043306f5bb0 > Author: Masami Hiramatsu > Date: Fri Feb 27 13:50:26 2015 +0900 > > perf buildid-cache: Add --purge FILE to remove all caches of FILE > > ----------------------- > > > I have done some more debugging and there is something wrong. > > The function > > build_id_cache__purge_path() is called and > > build_id_cache__list_build_ids() creates a list of file names located in /usr/bin of the buildid-cache. > > build_id_cache__remove_s() is called for each name in the list and tries to locate each file name > > in directory .buildid/YY/ZZZ..ZZZ which fails because > > build_id_cache__linkname() expects a buildid and gets a file name. > > The file name bash is treated as .buildid/ba/sh which does not exist. > > probably this got broken when the /elf, /probe separation was added, > humm, unsure if a 'git bisect' would help here... > > Masami? Should it work for a directory instead of a file too? I need to investigate it too. Thanks, > > > This seems to be a simple mistake so I wonder if I do something wrong. > > - Arnaldo -- Masami Hiramatsu