Messages in this thread | | | From | Bill Davidsen <> | Subject | Re: per-process shared information | Date | Tue, 19 Oct 2004 11:09:46 -0400 |
| |
Andrea Arcangeli wrote: > On Fri, Oct 15, 2004 at 09:19:13AM -0400, Albert Cahalan wrote: > >>I don't see why it is such trouble to provide the old data. > > > I agree with you w.r.t. binary compatibility, here it's even a "source > compatibility" matter, a recompile wouldn't fix it. > > However I wasn't exactly advocating to keep it 100% backwards > compatible in this case: somebody already broke it from 2.5.x to > 2.6.9-rc, and since there was a very good reason for that, we should > probably declare it broken. Here there has been a very strong technical > reason to break statm, but they didn't break binary and source > compatibility gratuitously like some solaris kernel developer seems to > think in some blog. > > the problem is that when ps xav wants to know the RSS it reads statm, > so we just cannot hurt ps xav to show the "old shared" information that > would be extremely slow to collect. > > I was only not happy about dropping the old feature completely instead > of providing it with a different new API. Now I think the solution Hugh > just proposed with the anon_rss should mimic the old behaviour well > enough and it's probably the right way to go, it's still not literally > the same, but I doubt most people from userspace could notice the > difference, and most important it provides useful information, which is > the number of _physical_ pages mapped that aren't anonymous memory, this > is very valuable info and it's basically the same info that people was > getting from the old "shared". So I like it.
I think that's clearly the right solution. Going to significant effort to produce compatible but incorrect values and/or formats is not desirable. I've seen this with users and applications, too, complaining that the new output doesn't match the old, even when the old was clearly wrong.
-- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |