Messages in this thread | | | Date | Wed, 7 Oct 2009 08:43:55 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC][PATCH] perf tools: Merge trace.info content into perf.data |
| |
* Ingo Molnar <mingo@elte.hu> wrote:
> * Frederic Weisbecker <fweisbec@gmail.com> wrote: > > > Hi, > > > > Here is an attempt to remove the trace.info file. It works well for > > me, the reason for it to be an RFC is that I have doubts about the > > backward compatibility. > > > > A file created by perf after his patch is unsupported by previous > > version because the size of the headers have increased. > > That's OK i think in terms of trace.info - trace.info was a temporary > hack to begin with. > > > That said, it's two new fields that have been added in the end of the > > headers, and those could be ignored by previous versions if they just > > handled the dynamic header size and then ignore the unknow part. The > > offsets guarantee the compatibility. > > Yes, that's how it should work. > > > But previous versions handle the header size using its static size, > > not dynamic, then it's not backward compatible. > > > > Anyway, I'm not sure exactly how to handle that. > > That's a bug in the previous version - mind doing a standalone fix for > that so we can mark it Cc: stable?
Meanwhile i've applied your two patches - they are clear steps forward. We'll need the -stable fix so that the new perf.data can be read. (and even that only affects -R afaics - so normal perf record / perf report is compatible.)
Btw., we also need a patch for new perf to read older perf.data files [non-trace.info ones], as those are not working either:
$ perf report Fatal: incompatible file format
( We dont want to push it - i.e. i dont think we need to support old perf.data + trace.info combos. )
Ingo
| |