http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54487
--- Comment #21 from davidxl at google dot com 2012-09-11 18:08:26 UTC --- Assuming the size of histogram for the same file does not vary that much, is it better to round the size to the next power of 2 -- 60 entries will need print out 64 etc? David On Tue, Sep 11, 2012 at 11:04 AM, Teresa Johnson <tejohn...@google.com> wrote: > 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 my debugging, and if it is no longer valid, throw everything away and 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 > > > > -- > Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
