Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-19 Thread Rémi Denis-Courmont
Le keskiviikkona 19. heinäkuuta 2023, 0.32.26 EEST Lynne a écrit : > > User-space access to the cycle counter has been deemed a security threat > > due to the Cycle Drift attack, and is disabled as of OpenSBI 1.3. > > > > If FFmpeg does not support Linux perf, FFmpeg will get _no_ performance > >

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-18 Thread Lynne
Jul 17, 2023, 20:09 by r...@remlab.net: > Le maanantaina 17. heinäkuuta 2023, 20.48.40 EEST Lynne a écrit : > >> >> > But I still argue that that is, either way, completely negligible >> >> > compared >> >> > to the *existing* overhead. Each loop is making 4 system calls, and >> >> > each >> >> >

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-17 Thread Rémi Denis-Courmont
Le maanantaina 17. heinäkuuta 2023, 20.48.40 EEST Lynne a écrit : > >> > But I still argue that that is, either way, completely negligible > >> > compared > >> > to the *existing* overhead. Each loop is making 4 system calls, and > >> > each > >> > of those system call requires a direct call (to

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-17 Thread Lynne
Jul 17, 2023, 07:18 by r...@remlab.net: > Le sunnuntaina 16. heinäkuuta 2023, 23.32.21 EEST Lynne a écrit : > >> Introducing additional overhead in the form of a dereference is a point >> where instability can creep in. Can you guarantee that a context will >> always remain in L1D cache, >> > >

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-16 Thread Rémi Denis-Courmont
Le sunnuntaina 16. heinäkuuta 2023, 23.32.21 EEST Lynne a écrit : > Introducing additional overhead in the form of a dereference is a point > where instability can creep in. Can you guarantee that a context will > always remain in L1D cache, L1D is not involved here. In version 2, the pointers

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-16 Thread Lynne
Jul 15, 2023, 22:13 by r...@remlab.net: > Le lauantaina 15. heinäkuuta 2023, 20.43.26 EEST Lynne a écrit : > >> Jul 15, 2023, 10:26 by r...@remlab.net: >> > Le lauantaina 15. heinäkuuta 2023, 11.05.51 EEST Lynne a écrit : >> >> Jul 14, 2023, 20:29 by r...@remlab.net: >> >> > This makes all calls

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-15 Thread Rémi Denis-Courmont
Le lauantaina 15. heinäkuuta 2023, 20.43.26 EEST Lynne a écrit : > Jul 15, 2023, 10:26 by r...@remlab.net: > > Le lauantaina 15. heinäkuuta 2023, 11.05.51 EEST Lynne a écrit : > >> Jul 14, 2023, 20:29 by r...@remlab.net: > >> > This makes all calls to the bench start and stop functions via > >> >

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-15 Thread Lynne
Jul 15, 2023, 10:26 by r...@remlab.net: > Le lauantaina 15. heinäkuuta 2023, 11.05.51 EEST Lynne a écrit : > >> Jul 14, 2023, 20:29 by r...@remlab.net: >> > This makes all calls to the bench start and stop functions via >> > function pointers. While the primary goal is to support run-time >> >

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-15 Thread Rémi Denis-Courmont
Le lauantaina 15. heinäkuuta 2023, 11.05.51 EEST Lynne a écrit : > Jul 14, 2023, 20:29 by r...@remlab.net: > > This makes all calls to the bench start and stop functions via > > function pointers. While the primary goal is to support run-time > > selection of the performance measurement back-end

Re: [FFmpeg-devel] [PATCH 4/7] checkasm: use pointers for start/stop functions

2023-07-15 Thread Lynne
Jul 14, 2023, 20:29 by r...@remlab.net: > This makes all calls to the bench start and stop functions via > function pointers. While the primary goal is to support run-time > selection of the performance measurement back-end in later commits, > this has the side benefit of containing platform