PING^2
@Honza: ?
On 1/29/21 2:33 PM, Martin Liška wrote:
PING^1
On 1/25/21 1:51 PM, Martin Liška wrote:
On 1/22/21 3:33 PM, Jan Hubicka wrote:
It is definitly doable (gcov machinery is quite flexible WRT having more
types of counters).
Yes, that would introduce back the dropped TOPN counters which I intentionally
dropped.
We could bring back topn counters or the easier dominating vlaue ones
and add command line option. However perhaps better in long term would
be keep adding mmap ifdefs for targets where it is important...
Kernel guys seems to be getting on profile feedback with clang, so we
should keep in mind posibility of supporting that as well.
Sure, that should not be so difficult. They should handle it in their kernel
run-time.
We could however also ask users to either resort to
-fno-profile-values or implement mmap equivalent ifdefs to libgcov if
they really care about malloc profiling.
Seems reasonable to me.
Well, the current approach makes some assumptions on mmap (and malloc), but
they seem reasonable to me. I don't expect anybody building Mingw Firefox PGO
build,
it's likely unsupported configuration.
It is possible to build Firefox with mingw on windows and I would
expected feedback to work.
https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Compiling_Mozilla_With_Mingw
However this is not only about Firefox - we notice problems with Firefox
since it is only real word app where we look at PGO more systematically.
But we definitly should aim for PGO to be useful for apps of similar
complexity. It would be nice to incrase this testing coverage.
I see.
Another observation about the tcmalloc 'malloc' implementation. It hangs in a
PGO build,
but libgcov would be happy if NULL would be returned.
Yep, I would expect other folks to try to PGO optimize malloc
implementations an we could run into variety of issues...
Ok, can we go with the suggested mmap patch for now?
Thanks,
Martin
Honza
Martin
So personally I do not see this as a must feature (and I think Martin
was really looking forward to drop the former topn profile
implementation :)
Another intersting case would be, of course, profiling of kernel...
Honza
