| Message ID | 1360128076-8555-1-git-send-email-iamjoonsoo.kim@lge.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 6, 2013 at 6:21 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote: > If we want load epoch_cyc and epoch_ns atomically, > we should update epoch_cyc_copy first of all. > This notify reader that updating is in progress. If you think the patch is finished, put it into Russell's patch tracker: http://www.arm.linux.org.uk/developer/patches/ Yours, Linus Walleij
Hello, Linus. 2013/2/6 Linus Walleij <linus.walleij@linaro.org>: > On Wed, Feb 6, 2013 at 6:21 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote: > >> If we want load epoch_cyc and epoch_ns atomically, >> we should update epoch_cyc_copy first of all. >> This notify reader that updating is in progress. > > If you think the patch is finished, put it into Russell's patch tracker: > http://www.arm.linux.org.uk/developer/patches/ Ah... Okay. Thanks for notifying me.
On Wed, Feb 06, 2013 at 10:33:53AM +0100, Linus Walleij wrote: > On Wed, Feb 6, 2013 at 6:21 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote: > > > If we want load epoch_cyc and epoch_ns atomically, > > we should update epoch_cyc_copy first of all. > > This notify reader that updating is in progress. > > If you think the patch is finished, put it into Russell's patch tracker: > http://www.arm.linux.org.uk/developer/patches/ Yea, this patch looks like the right thing... and yes, into the patch system please.
Hello, Russell. On Wed, Feb 06, 2013 at 04:33:55PM +0000, Russell King - ARM Linux wrote: > On Wed, Feb 06, 2013 at 10:33:53AM +0100, Linus Walleij wrote: > > On Wed, Feb 6, 2013 at 6:21 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote: > > > > > If we want load epoch_cyc and epoch_ns atomically, > > > we should update epoch_cyc_copy first of all. > > > This notify reader that updating is in progress. > > > > If you think the patch is finished, put it into Russell's patch tracker: > > http://www.arm.linux.org.uk/developer/patches/ > > Yea, this patch looks like the right thing... and yes, into the patch > system please. I try to put it into patch tracker, but I fail to put it. I use following command. git send-email --to patches@arm.linux.org.uk 0001-ARM-sched-correct~~~~~ Am I wrong? Could you teach me how to put patch into your patch tracker? I already read "help" on your website, but I can't find any stuff for "git send-email". Thanks. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
On Fri, Feb 08, 2013 at 03:51:25PM +0900, Joonsoo Kim wrote: > I try to put it into patch tracker, but I fail to put it. > I use following command. > > git send-email --to patches@arm.linux.org.uk 0001-ARM-sched-correct~~~~~ > > Am I wrong? > Could you teach me how to put patch into your patch tracker? > I already read "help" on your website, but I can't find any stuff for > "git send-email". I've never used git to send email, so I'm afraid I can't help with that. Maybe someone with more experience with sending email from git can comment?
On Fri, 8 Feb 2013, Russell King - ARM Linux wrote: > On Fri, Feb 08, 2013 at 03:51:25PM +0900, Joonsoo Kim wrote: > > I try to put it into patch tracker, but I fail to put it. > > I use following command. > > > > git send-email --to patches@arm.linux.org.uk 0001-ARM-sched-correct~~~~~ > > > > Am I wrong? > > Could you teach me how to put patch into your patch tracker? > > I already read "help" on your website, but I can't find any stuff for > > "git send-email". > > I've never used git to send email, so I'm afraid I can't help with that. > Maybe someone with more experience with sending email from git can > comment? The commit text for the patch needs to contain the following 2 lines at the very bottom in order to match the patch system's expectations: PATCH FOLLOWS KernelVersion: v3.8 The KernelVersion value needs to be adjusted of course. Note: I never tried it myself but it ought to work. Nicolas
2013/2/9 Nicolas Pitre <nicolas.pitre@linaro.org>: > On Fri, 8 Feb 2013, Russell King - ARM Linux wrote: > >> On Fri, Feb 08, 2013 at 03:51:25PM +0900, Joonsoo Kim wrote: >> > I try to put it into patch tracker, but I fail to put it. >> > I use following command. >> > >> > git send-email --to patches@arm.linux.org.uk 0001-ARM-sched-correct~~~~~ >> > >> > Am I wrong? >> > Could you teach me how to put patch into your patch tracker? >> > I already read "help" on your website, but I can't find any stuff for >> > "git send-email". >> >> I've never used git to send email, so I'm afraid I can't help with that. >> Maybe someone with more experience with sending email from git can >> comment? > > The commit text for the patch needs to contain the following 2 lines at > the very bottom in order to match the patch system's expectations: > > PATCH FOLLOWS > KernelVersion: v3.8 > > The KernelVersion value needs to be adjusted of course. > > Note: I never tried it myself but it ought to work. Yes!!!! It works! Thanks!!! > Nicolas > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c index fc6692e..bd6f56b 100644 --- a/arch/arm/kernel/sched_clock.c +++ b/arch/arm/kernel/sched_clock.c @@ -93,11 +93,11 @@ static void notrace update_sched_clock(void) * detectable in cyc_to_fixed_sched_clock(). */ raw_local_irq_save(flags); - cd.epoch_cyc = cyc; + cd.epoch_cyc_copy = cyc; smp_wmb(); cd.epoch_ns = ns; smp_wmb(); - cd.epoch_cyc_copy = cyc; + cd.epoch_cyc = cyc; raw_local_irq_restore(flags); }
If we want load epoch_cyc and epoch_ns atomically, we should update epoch_cyc_copy first of all. This notify reader that updating is in progress. If we update epoch_cyc first like as current implementation, there is subtle error case. Look at the below example. <Initial Condition> cyc = 9 ns = 900 cyc_copy = 9 == CASE 1 == <CPU A = reader> <CPU B = updater> write cyc = 10 read cyc = 10 read ns = 900 write ns = 1000 write cyc_copy = 10 read cyc_copy = 10 output = (10, 900) == CASE 2 == <CPU A = reader> <CPU B = updater> read cyc = 9 write cyc = 10 write ns = 1000 read ns = 1000 read cyc_copy = 9 write cyc_copy = 10 output = (9, 1000) If atomic read is ensured, output should be (9, 900) or (10, 1000). But, output in example case are not. So, change updating sequence in order to correct this problem. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>