From: "Dilger, Andreas" <andreas.dilger@intel.com> To: NeilBrown <neilb@suse.com> Cc: James Simmons <jsimmons@infradead.org>, "Drokin, Oleg" <oleg.drokin@intel.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "Lustre Development List" <lustre-devel@lists.lustre.org> Subject: Re: [lustre-devel] [PATCH 11/17] staging: lustre: libcfs: discard cfs_time_shift(). Date: Wed, 4 Apr 2018 08:10:44 +0000 [thread overview] Message-ID: <CB90FEDF-3F67-46A7-8EC3-ABC788E7978C@intel.com> (raw) In-Reply-To: <87muyl1bzs.fsf@notabene.neil.brown.name> On Apr 2, 2018, at 16:26, NeilBrown <neilb@suse.com> wrote: > On Mon, Apr 02 2018, Dilger, Andreas wrote: >> On Mar 30, 2018, at 13:02, James Simmons <jsimmons@infradead.org> wrote: >>>> This function simply multiplies by HZ and adds jiffies. >>>> This is simple enough to be opencoded, and doing so >>>> makes the code easier to read. >>>> >>>> Same for cfs_time_shift_64() >>> >>> Reviewed-by: James Simmons <jsimmons@infradead.org> >> >> Hmm, I thought we were trying to get rid of direct HZ usage in modules, >> because of tickless systems, and move to e.g. msecs_to_jiffies() or similar? > > Are we? I hadn't heard but I could easily have missed it. > Documentation/scheduler/completion.txt does say > > Timeouts are preferably calculated with > msecs_to_jiffies() or usecs_to_jiffies(). > > but is isn't clear what they are preferred to. Do you remember where > you heard? or have a reference? I thought the goal was to avoid hard-coding the HZ value so that kernels could have variable clock rates in the future. Cheers, Andreas > $ git grep ' \* *HZ' |wc > 2244 15679 170016 > $ git grep msecs_to_jiffies | wc > 3301 13151 276725 > > so msecs_to_jiffies is slightly more popular than "* HZ" (even if you add > in "HZ *"). But that could just be a preference for using milliseconds > over using seconds. > > $ git grep msecs_to_jiffies | grep -c '[0-9]000' > 587 > > so there are only 587 places that msecs_to_jiffies is clearly used in > place of multiplying by HZ. > > If we were to pursue this, I would want to add secs_to_jiffies() to > include/linux/jiffies.h and use that. > > Thanks, > NeilBrown > _______________________________________________ > lustre-devel mailing list > lustre-devel@lists.lustre.org > http://lists.lustre.org/listinfo.cgi/lustre-devel-lustre.org Cheers, Andreas -- Andreas Dilger Lustre Principal Architect Intel Corporation
WARNING: multiple messages have this Message-ID (diff)
From: Dilger, Andreas <andreas.dilger@intel.com> To: NeilBrown <neilb@suse.com> Cc: James Simmons <jsimmons@infradead.org>, "Drokin, Oleg" <oleg.drokin@intel.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Lustre Development List <lustre-devel@lists.lustre.org> Subject: [lustre-devel] [PATCH 11/17] staging: lustre: libcfs: discard cfs_time_shift(). Date: Wed, 4 Apr 2018 08:10:44 +0000 [thread overview] Message-ID: <CB90FEDF-3F67-46A7-8EC3-ABC788E7978C@intel.com> (raw) In-Reply-To: <87muyl1bzs.fsf@notabene.neil.brown.name> On Apr 2, 2018, at 16:26, NeilBrown <neilb@suse.com> wrote: > On Mon, Apr 02 2018, Dilger, Andreas wrote: >> On Mar 30, 2018, at 13:02, James Simmons <jsimmons@infradead.org> wrote: >>>> This function simply multiplies by HZ and adds jiffies. >>>> This is simple enough to be opencoded, and doing so >>>> makes the code easier to read. >>>> >>>> Same for cfs_time_shift_64() >>> >>> Reviewed-by: James Simmons <jsimmons@infradead.org> >> >> Hmm, I thought we were trying to get rid of direct HZ usage in modules, >> because of tickless systems, and move to e.g. msecs_to_jiffies() or similar? > > Are we? I hadn't heard but I could easily have missed it. > Documentation/scheduler/completion.txt does say > > Timeouts are preferably calculated with > msecs_to_jiffies() or usecs_to_jiffies(). > > but is isn't clear what they are preferred to. Do you remember where > you heard? or have a reference? I thought the goal was to avoid hard-coding the HZ value so that kernels could have variable clock rates in the future. Cheers, Andreas > $ git grep ' \* *HZ' |wc > 2244 15679 170016 > $ git grep msecs_to_jiffies | wc > 3301 13151 276725 > > so msecs_to_jiffies is slightly more popular than "* HZ" (even if you add > in "HZ *"). But that could just be a preference for using milliseconds > over using seconds. > > $ git grep msecs_to_jiffies | grep -c '[0-9]000' > 587 > > so there are only 587 places that msecs_to_jiffies is clearly used in > place of multiplying by HZ. > > If we were to pursue this, I would want to add secs_to_jiffies() to > include/linux/jiffies.h and use that. > > Thanks, > NeilBrown > _______________________________________________ > lustre-devel mailing list > lustre-devel at lists.lustre.org > http://lists.lustre.org/listinfo.cgi/lustre-devel-lustre.org Cheers, Andreas -- Andreas Dilger Lustre Principal Architect Intel Corporation
next prev parent reply other threads:[~2018-04-04 8:10 UTC|newest] Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-29 4:26 [PATCH 00/17] staging: Assorted lustre cleanup NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-29 4:26 ` [PATCH 05/17] staging: lustre: remove unneeded include NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:57 ` James Simmons 2018-03-30 18:57 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 11/17] staging: lustre: libcfs: discard cfs_time_shift() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:02 ` James Simmons 2018-03-30 19:02 ` [lustre-devel] " James Simmons 2018-04-02 19:34 ` Dilger, Andreas 2018-04-02 19:34 ` [lustre-devel] " Dilger, Andreas 2018-04-02 22:26 ` NeilBrown 2018-04-02 22:26 ` [lustre-devel] " NeilBrown 2018-04-04 8:10 ` Dilger, Andreas [this message] 2018-04-04 8:10 ` Dilger, Andreas 2018-04-04 22:00 ` NeilBrown 2018-04-04 22:00 ` NeilBrown 2018-03-29 4:26 ` [PATCH 17/17] staging: lustre: remove cruft from libcfs/linux/libcfs.h NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:07 ` James Simmons 2018-03-30 19:07 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 07/17] staging: lustre: ldlm: free resource when ldlm_lock_create() fails NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:58 ` James Simmons 2018-03-30 18:58 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 01/17] staging: lustre: remove invariant in cl_io_read_ahead() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:56 ` James Simmons 2018-03-30 18:56 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 02/17] staging: lustre: remove unused ldlm_completion_ast_async() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:57 ` James Simmons 2018-03-30 18:57 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 04/17] staging: lustre: remove unused hash tables NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:57 ` James Simmons 2018-03-30 18:57 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 03/17] staging: lustre: LNET excludes USERIO NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:09 ` James Simmons 2018-03-30 19:09 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 10/17] staging: lustre: libcfs: discard cfs_time_add/sub NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:00 ` James Simmons 2018-03-30 19:00 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 13/17] staging: lustre: libcfs: remove cfs_timeout_cap() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:03 ` James Simmons 2018-03-30 19:03 ` [lustre-devel] " James Simmons 2018-04-02 19:38 ` Dilger, Andreas 2018-04-02 19:38 ` [lustre-devel] " Dilger, Andreas 2018-04-02 22:34 ` NeilBrown 2018-04-02 22:34 ` [lustre-devel] " NeilBrown 2018-03-29 4:26 ` [PATCH 14/17] staging: lustre: discard cfs_duration_sec() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:02 ` James Simmons 2018-03-30 19:02 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 08/17] staging: lustre: add container_of_safe() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:59 ` James Simmons 2018-03-30 18:59 ` [lustre-devel] " James Simmons 2018-04-10 1:37 ` Cory Spitz 2018-04-11 21:19 ` NeilBrown 2018-04-23 13:16 ` Greg Kroah-Hartman 2018-04-23 13:16 ` [lustre-devel] " Greg Kroah-Hartman 2018-03-29 4:26 ` [PATCH 09/17] staging: lustre: cfs_time_current() -> jiffies NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:00 ` James Simmons 2018-03-30 19:00 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 16/17] staging: lustre: discard linux-time.h NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:03 ` James Simmons 2018-03-30 19:03 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 12/17] staging: lustre: libcfs: discard cfs_time_after() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:01 ` James Simmons 2018-03-30 19:01 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 06/17] staging: lustre: tidy up ldlm_resource_putref() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 18:58 ` James Simmons 2018-03-30 18:58 ` [lustre-devel] " James Simmons 2018-03-29 4:26 ` [PATCH 15/17] staging: lustre: discard cfs_time_before_64() NeilBrown 2018-03-29 4:26 ` [lustre-devel] " NeilBrown 2018-03-30 19:03 ` James Simmons 2018-03-30 19:03 ` [lustre-devel] " James Simmons
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