-----Ursprüngliche Nachricht----- Gesendet: Dienstag, 26 März 2013 um 12:13:26 Uhr Von: "Jan Hubicka" <hubicka@xxxxxx> An: "Markus Trippelsdorf" <markus@xxxxxxxxxxxxxxx> Betreff: Re: Compiler speed (vanilla vs. LTO, PGO and LTO+PGO) > Yes, the binary size is 8-10% smaller. Unfortunately there are no performance > improvements. > > LTO+PGO-disable-plugin: > -rwxr-xr-x 1 markus markus 15025568 Mar 25 15:49 cc1 > -rwxr-xr-x 1 markus markus 16198584 Mar 25 15:49 cc1plus > -rwxr-xr-x 1 markus markus 13907328 Mar 25 15:49 lto1 > -rwxr-xr-x 4 markus markus 492360 Mar 25 15:49 c++ > -rwxr-xr-x 1 markus markus 488240 Mar 25 15:49 cpp > -rwxr-xr-x 3 markus markus 488216 Mar 25 15:49 gcc > > Firefox: > LTO+PGO-disable-plugin: 4590.55s user 273.70s system 343% cpu 23:34.65 total > > kernel: > LTO+PGO-disable-plugin: > 344.11s user 23.59s system 322% cpu 1:54.08 total 340.94s user 23.65s system 326% cpu 1:51.56 total 339.66s user 23.41s system 329% cpu 1:50.09 total Interesting, I was able to get faste LTO+PGO compile times than non-LTO,PGO. I however did testng only on combine.c compliation, so not very scientific. There are some cases FDO information is not streamed well in all cases. I will post patch for that later today. Perhaps it will make situation bit better. Honza Thanks for all the input for the question "is it useful to compile gcc 4.8.0 with the lto option?" Best regard!
