Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1646764

Re: RFC: better timer interface

Show all headers | View raw

On Sun, May 21, 2017 at 8:14 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Sun, 21 May 2017, Thomas Gleixner wrote:
>> On Tue, 16 May 2017, Arnd Bergmann wrote:
>> > On Tue, May 16, 2017 at 5:51 PM, Christoph Hellwig <hch@lst.de> wrote:
>> > > Yes, that sounds useful to me as well.  As you said it's an independent
>> > > but somewhat related change.  I can add it to my series, but I'll
>> > > need a suggestions for a good and short name.  That already was the
>> > > hardest part for the setup side :)
>> >
>> > If we keep the unusual *_timer() naming (rather than timer_*() as hrtimer
>> > has), we could use one of
>> >
>> > a) start_timer(struct timer_list *timer, unsigned long ms);
>> > b) restart_timer(struct timer_list *timer, unsigned long ms);
>> > c) mod_timer_ms(struct timer_list *timer, unsigned long ms);
>> >     mod_timer_sec(struct timer_list *timer, unsigned long sec);
>>
>> Please make new functions prefixed with timer_ and get rid of that old
>> interface completely. It's horrible.
>>
>> timer_init()
>> timer_start(timer, ms, abs)
>
> I'm not even sure, whether we need absolute timer wheel timers at
> all, because most use cases are relative to now.
>
> But it's easy enough to provide them. All we need for that is something
> like
>
>         unsigned long time_msec;
>
> which gets incremented every tick by the appropriate amount of
> milliseconds.
>
> Having that would also allow to replace all the
>
>        end = jiffies + msec_to_jiffies(xxx);
>
>        while (time_before(jiffies, end))
>              ....
>
> constructs with a milliseconds based machinery. So we can remove all
> *_to_jiffies() interfaces over time.

A lot of those users could probably just ktime_get()/ktime_before() here,
as they would by definition not be performance critical.

I don't see a way to just tk->tkr_mono.base but with a ktime_get_coarse()
we could just return the ktime_t of the last tick and not even need a seqlock
on 64-bit architectures, or have to introduce a new API.

        Arnd

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

RFC: better timer interface Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
  [PATCH 3/9] kthread: remove unused macros Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
    Re: [PATCH 3/9] kthread: remove unused macros Petr Mladek <pmladek@suse.com> - 2017-05-17 14:20 +0200
      Re: [PATCH 3/9] kthread: remove unused macros Christoph Hellwig <hch@lst.de> - 2017-05-18 10:30 +0200
  [PATCH 8/9] tlclk: switch switchover_timer to a modern timer Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
  [PATCH 6/9] s390: switch topology_timer to a modern timer Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
  [PATCH 4/9] workqueue: switch to modern timers Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
  [PATCH 7/9] s390: switch lgr timer to a modern timer Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
  [PATCH 9/9] timers: remove old timer initialization macros Christoph Hellwig <hch@lst.de> - 2017-05-16 13:50 +0200
    Re: [PATCH 9/9] timers: remove old timer initialization macros Arnd Bergmann <arnd@arndb.de> - 2017-05-16 21:50 +0200
      Re: [PATCH 9/9] timers: remove old timer initialization macros Christoph Hellwig <hch@lst.de> - 2017-05-18 10:30 +0200
  [PATCH 2/9] timers: provide a "modern" variant of timers Christoph Hellwig <hch@lst.de> - 2017-05-16 14:00 +0200
    Re: [PATCH 2/9] timers: provide a "modern" variant of timers Randy Dunlap <rdunlap@infradead.org> - 2017-05-16 21:30 +0200
    Re: [PATCH 2/9] timers: provide a "modern" variant of timers Arnd Bergmann <arnd@arndb.de> - 2017-05-16 22:10 +0200
      Re: [PATCH 2/9] timers: provide a "modern" variant of timers Christoph Hellwig <hch@lst.de> - 2017-05-18 10:30 +0200
        Re: [PATCH 2/9] timers: provide a "modern" variant of timers Christoph Hellwig <hch@lst.de> - 2017-05-18 10:50 +0200
          Re: [PATCH 2/9] timers: provide a "modern" variant of timers Arnd Bergmann <arnd@arndb.de> - 2017-05-18 11:00 +0200
            Re: [PATCH 2/9] timers: provide a "modern" variant of timers Christoph Hellwig <hch@lst.de> - 2017-05-21 09:10 +0200
              Re: [PATCH 2/9] timers: provide a "modern" variant of timers Arnd Bergmann <arnd@arndb.de> - 2017-05-21 14:30 +0200
          Re: [PATCH 2/9] timers: provide a "modern" variant of timers Thomas Gleixner <tglx@linutronix.de> - 2017-05-21 20:00 +0200
            Re: [PATCH 2/9] timers: provide a "modern" variant of timers Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-21 20:30 +0200
    RE: [PATCH 2/9] timers: provide a "modern" variant of timers David Laight <David.Laight@ACULAB.COM> - 2017-05-19 12:50 +0200
      Re: [PATCH 2/9] timers: provide a "modern" variant of timers 'Christoph Hellwig' <hch@lst.de> - 2017-05-21 09:00 +0200
  [PATCH 5/9] powerpc/numa: switch topology_timer to modern timer Christoph Hellwig <hch@lst.de> - 2017-05-16 14:00 +0200
  Re: RFC: better timer interface Arnd Bergmann <arnd@arndb.de> - 2017-05-16 17:50 +0200
    Re: RFC: better timer interface Christoph Hellwig <hch@lst.de> - 2017-05-16 18:00 +0200
      Re: RFC: better timer interface Arnd Bergmann <arnd@arndb.de> - 2017-05-16 22:30 +0200
        Re: RFC: better timer interface Christoph Hellwig <hch@lst.de> - 2017-05-18 10:30 +0200
        Re: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-21 19:20 +0200
          Re: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-21 20:20 +0200
            Re: RFC: better timer interface Arnd Bergmann <arnd@arndb.de> - 2017-05-22 13:30 +0200
              Re: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-22 21:30 +0200
            RE: RFC: better timer interface David Laight <David.Laight@ACULAB.COM> - 2017-05-23 13:40 +0200
              RE: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-23 14:00 +0200
                RE: RFC: better timer interface David Laight <David.Laight@ACULAB.COM> - 2017-05-23 15:00 +0200
                RE: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-23 15:10 +0200
          Re: RFC: better timer interface Arnd Bergmann <arnd@arndb.de> - 2017-05-22 15:40 +0200
            Re: RFC: better timer interface Thomas Gleixner <tglx@linutronix.de> - 2017-05-22 21:20 +0200

csiph-web