http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54487
--- Comment #20 from Teresa Johnson <tejohnson at google dot com> 2012-09-11 18:05:13 UTC --- On Tue, Sep 11, 2012 at 10:44 AM, Xinliang David Li <davi...@google.com> wrote: > How much saving do we get by not writing out the 0 entries? With the > proposed change, how less frequent is the problem occuring? Let me get back with some stats. Each histogram entry requires 5 words, and there are a max of 252 entries. In the few cases I checked just now, we were printing about 60 entries per summary, with 3 summaries per gcda file. So printing the whole thing in these cases would require 5*(252-60)*3 = 2880 extra words, or 11520 bytes. Unfortunately, that is a significant increase over the current sizes of those files, which are currently only double or triple that. I also need to verify that changing this would reduce the frequency. A couple other possibilities since this is not frequent: - change the existing error to a warning (as we do under flag_profile_correction) - after finishing reading the counts, re-read the tag as I am doing in my debugging, and if it is no longer valid, throw everything away and re-read the file. - check the counters after reading each one, and if it is > sum_max, ignore it and abort the profile read with a warning but continue compiling. Obviously the best solution would be to figure out how the lock is being lost/ignored and fix that, but that may take some time. Teresa > > David > > On Tue, Sep 11, 2012 at 10:38 AM, Teresa Johnson <tejohn...@google.com> wrote: >> On Tue, Sep 11, 2012 at 10:29 AM, hjl.tools at gmail dot com >> <gcc-bugzi...@gcc.gnu.org> wrote: >>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54487 >>> >>> --- Comment #17 from H.J. Lu <hjl.tools at gmail dot com> 2012-09-11 >>> 17:29:15 UTC --- >>> Thanks for looking into it. This is a long standing problem. >>> I have seen random profiledbootstrap failures for a long time. >> >> Thanks for confirming that this has happened prior. Unfortunately the >> addition of the histogram is likely making this more frequent, due to >> the changing summary sizes after merging. One way to deal with this >> for now might be to write all histogram entries (even the 0 ones) into >> the summary to keep the size static. >> >> Honza, what do you think? >> >> Teresa >> >>> >>> -- >>> Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email >>> ------- You are receiving this mail because: ------- >>> You are on the CC list for the bug. >> >> >> >> -- >> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
