On Mon, Aug 10, 2020 at 03:02:32PM +0300, Paul Gofman wrote:
On 8/10/20 14:55, Arkadiusz Hiler wrote:
On Mon, Aug 10, 2020 at 02:45:49PM +0300, Paul Gofman wrote:
On 8/10/20 14:32, Paul Gofman wrote:
On 8/10/20 13:55, Arkadiusz Hiler wrote:
Sleep() and GetTickCount() work on Windows in 15.6ms increments.
Some programs (DOSBox) are depending on this behavior and are assuming that the return value of GetTickCount() will change during sleeping.
Currently we are updating shared counters used by GetTickCount() every 16ms + on each server request, and our Sleep() implementation has resolution of 1ms, which causes DOSBox to hang.
This patch changes Sleep() (and SleepEx()) to behave the same way as on Windows and makes sure that GetTickCount() will be updated during sleeping by decreasing the update interval to 15ms (worst case, without any server calls).
This fixes Doom II from Steam.
I also did notice that Sleep on Windows use to work with 15.6ms quantum some time ago. But the important part which is missed here is that Sleep behaviour is affected (at least) by timeBeginPeriod() / timeEndPeriod() winmm functions (as I recalled now after rerunning my old test program and wondering why I see 1ms sleep quantum). E. g., if I call timeBeingPeriod(1) before testing Sleep actual time and GetTickCount change, the Sleep starts to behave very similar to how it works now in Wine: sleeps with 1ms quantum and GetTickCount() is not necessarily updated on wake. I think we can't ignore that behaviour, I did see the games playing with winmm functions, Sleep etc.
I was also initially going to say that maybe we would need to explicitly check if GetTickCount has changed during sleep, but the failing test on Win10 suggests that maybe Windows doesn't guarantee that also, just sleeps with 15.6ms quantum by default (unless changed by winmm).
PS If timeBeginPeriod() indeed sets the global time resolution for all processes as the docs suggest, I can guess there should be a field in KSHARED_USER_DATA which holds that resolution (there are a few related to timers, I did not ever test what exactly do they hold), and we should probably use those to store and retrieve timer resolution.
Indeed timeBeginPeriod() seems to affect the resolution of Sleep()
https://hiler.eu/p/0701eab8d523.txt https://testbot.winehq.org/JobDetails.pl?Key=76759&f109=exe64.report#k10...
This is completely unexpected... Thanks for pointing this out!
I guess I have to investigate whether it's truly global and if there is a field for that in KSHARED_USER_DATA.
That would be a bit funny - anything that depends on the default behavior will be broken while that process is running, and if it crashes/forgets to call timeEndPeriod() upon exit we are left in that broken state forever :-)
Please mind also NtSetTimerResolution() / NtQueryTimerResolution() functions (which is currently a stub in Wine). This all needs testing, but it would looks natural if winmm would actually call that one. All that probably means that it is NtDelayExecution() which needs to be fixed to favour current timer resolution (besides a load of functions related to various timers; but maybe those can be treated separately from these changes?). Unfortunately that makes things more complicated because NtDelayExecution is widely used by Wine itself and those places might rely on a (relatively) precise delays not to introduce great performance loss, so maybe those usages needs to be checked before changing that.
Lazy/temporary solution would to to bring back the old behavior of GetTickCount() - the 1ms resolution. This can be easily done by calling NtQueryPerformanceTimer() as it still uses monotic_counter() through unixlib. Most things seemed to be fine with this approach, not sure what would be the performance hit here though.
Also any programs reading counters directly from KSHARED_USER_DATA may still be broken.
I think I'll start exploring timeBeginPeriod() and NtSetTimerResolution() and implement the changes limited to Sleep*() for now.
Then, if this is fine with the reviewers we can see how hard it would be to extend this behavior over to NtDelayExecution().