* high precision timers @ 2021-05-02 14:10 Hyeonggon Yoo 2021-05-02 14:54 ` Greg KH 0 siblings, 1 reply; 4+ messages in thread From: Hyeonggon Yoo @ 2021-05-02 14:10 UTC (permalink / raw) To: kernelnewbies the 'timer wheel' - which has low resolution works at jiffy resolution. so usually it has precision of 1~10ms. and there's high resolution timers in kernel to have nanosecond resolution, but it doesn't seem to have nanosecond precision is there a way to deal with high precision timers in kernel? does it require specific hardware? _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: high precision timers 2021-05-02 14:10 high precision timers Hyeonggon Yoo @ 2021-05-02 14:54 ` Greg KH [not found] ` <CAB=+i9TRO_KUMuHb5ozwQqXjoRKV+4+JtgQEdrgNh-eK1vivBA@mail.gmail.com> 0 siblings, 1 reply; 4+ messages in thread From: Greg KH @ 2021-05-02 14:54 UTC (permalink / raw) To: Hyeonggon Yoo; +Cc: kernelnewbies On Sun, May 02, 2021 at 11:10:11PM +0900, Hyeonggon Yoo wrote: > the 'timer wheel' - which has low resolution works at jiffy resolution. > so usually it has precision of 1~10ms. > > and there's high resolution timers in kernel to have nanosecond resolution, > but it doesn't seem to have nanosecond precision > > is there a way to deal with high precision timers in kernel? What exactly are you needing here? And do you have hardware that provides both high precision and high resolution? thanks, greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 4+ messages in thread
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* Re: high precision timers [not found] ` <CAB=+i9TRO_KUMuHb5ozwQqXjoRKV+4+JtgQEdrgNh-eK1vivBA@mail.gmail.com> @ 2021-05-03 11:13 ` Valdis Klētnieks [not found] ` <CAB=+i9RVEvEBJVYz-MkMAtZHhsNbr4a88CCVmjkpQ4WevWWxkQ@mail.gmail.com> 0 siblings, 1 reply; 4+ messages in thread From: Valdis Klētnieks @ 2021-05-03 11:13 UTC (permalink / raw) To: Hyeonggon Yoo; +Cc: Greg KH, kernelnewbies [-- Attachment #1.1: Type: text/plain, Size: 271 bytes --] On Mon, 03 May 2021 00:56:17 +0900, Hyeonggon Yoo said: > I mean, is there an API that guarantees high precision (non architecture > dependent way) How do you guarantee high precision if you're on hardware that doesn't provide a high precision/resolution timer? [-- Attachment #1.2: Type: application/pgp-signature, Size: 832 bytes --] [-- Attachment #2: Type: text/plain, Size: 170 bytes --] _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 4+ messages in thread
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* Re: high precision timers [not found] ` <CAB=+i9RVEvEBJVYz-MkMAtZHhsNbr4a88CCVmjkpQ4WevWWxkQ@mail.gmail.com> @ 2021-05-03 15:15 ` loïc tourlonias 0 siblings, 0 replies; 4+ messages in thread From: loïc tourlonias @ 2021-05-03 15:15 UTC (permalink / raw) To: Hyeonggon Yoo; +Cc: Greg KH, Valdis Klētnieks, kernelnewbies [-- Attachment #1.1: Type: text/plain, Size: 916 bytes --] Hi On Mon, May 3, 2021 at 2:16 PM Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote: > Greg, and Valdis Thank you so much! It helped a lot! > > I thought there would be a way to do it because of high resolution. > > 2021년 5월 3일 (월) 오후 8:13, Valdis Klētnieks <valdis.kletnieks@vt.edu>님이 작성: > >> On Mon, 03 May 2021 00:56:17 +0900, Hyeonggon Yoo said: >> >> > I mean, is there an API that guarantees high precision (non architecture >> > dependent way) >> >> How do you guarantee high precision if you're on hardware that doesn't >> provide a high precision/resolution timer? >> > If you don't have any hardware support, the Linux kernel can't magically count faster than its system tick. ^^ > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > [-- Attachment #1.2: Type: text/html, Size: 2102 bytes --] [-- Attachment #2: Type: text/plain, Size: 170 bytes --] _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-05-02 14:10 high precision timers Hyeonggon Yoo
2021-05-02 14:54 ` Greg KH
[not found] ` <CAB=+i9TRO_KUMuHb5ozwQqXjoRKV+4+JtgQEdrgNh-eK1vivBA@mail.gmail.com>
2021-05-03 11:13 ` Valdis Klētnieks
[not found] ` <CAB=+i9RVEvEBJVYz-MkMAtZHhsNbr4a88CCVmjkpQ4WevWWxkQ@mail.gmail.com>
2021-05-03 15:15 ` loïc tourlonias
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