| Message ID | 1528851463-21140-23-git-send-email-ricardo.neri-calderon@linux.intel.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | Implement an HPET-based hardlockup detector | expand |
On 06/12/2018 05:57 PM, Ricardo Neri wrote: > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f2040d4..a8833c7 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2577,7 +2577,7 @@ > Format: [state][,regs][,debounce][,die] > > nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels > - Format: [panic,][nopanic,][num] > + Format: [panic,][nopanic,][num,][hpet] > Valid num: 0 or 1 > 0 - turn hardlockup detector in nmi_watchdog off > 1 - turn hardlockup detector in nmi_watchdog on This says that I can use "nmi_watchdog=hpet" without using 0 or 1. Is that correct? > @@ -2587,6 +2587,9 @@ > please see 'nowatchdog'. > This is useful when you use a panic=... timeout and > need the box quickly up again. > + When hpet is specified, the NMI watchdog will be driven > + by an HPET timer, if available in the system. Otherwise, > + the perf-based implementation will be used. > > These settings can be accessed at runtime via > the nmi_watchdog and hardlockup_panic sysctls. thanks,
On Tue, Jun 12, 2018 at 10:26:57PM -0700, Randy Dunlap wrote: > On 06/12/2018 05:57 PM, Ricardo Neri wrote: > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index f2040d4..a8833c7 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -2577,7 +2577,7 @@ > > Format: [state][,regs][,debounce][,die] > > > > nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels > > - Format: [panic,][nopanic,][num] > > + Format: [panic,][nopanic,][num,][hpet] > > Valid num: 0 or 1 > > 0 - turn hardlockup detector in nmi_watchdog off > > 1 - turn hardlockup detector in nmi_watchdog on > > This says that I can use "nmi_watchdog=hpet" without using 0 or 1. > Is that correct? Yes, this what I meant. In my view, if you set nmi_watchdog=hpet it implies that you want to activate the NMI watchdog. In this case, perf. I can see how this will be ambiguous for the case of perf and arch NMI watchdogs. Alternative, a new parameter could be added; such as nmi_watchdog_type. I didn't want to add it in this patchset as I think that a single parameter can handle the enablement and type of the NMI watchdog. What do you think? Thanks and BR, Ricardo -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 06/13/2018 05:58 PM, Ricardo Neri wrote: > On Tue, Jun 12, 2018 at 10:26:57PM -0700, Randy Dunlap wrote: >> On 06/12/2018 05:57 PM, Ricardo Neri wrote: >>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >>> index f2040d4..a8833c7 100644 >>> --- a/Documentation/admin-guide/kernel-parameters.txt >>> +++ b/Documentation/admin-guide/kernel-parameters.txt >>> @@ -2577,7 +2577,7 @@ >>> Format: [state][,regs][,debounce][,die] >>> >>> nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels >>> - Format: [panic,][nopanic,][num] >>> + Format: [panic,][nopanic,][num,][hpet] >>> Valid num: 0 or 1 >>> 0 - turn hardlockup detector in nmi_watchdog off >>> 1 - turn hardlockup detector in nmi_watchdog on >> >> This says that I can use "nmi_watchdog=hpet" without using 0 or 1. >> Is that correct? > > Yes, this what I meant. In my view, if you set nmi_watchdog=hpet it > implies that you want to activate the NMI watchdog. In this case, perf. > > I can see how this will be ambiguous for the case of perf and arch NMI > watchdogs. > > Alternative, a new parameter could be added; such as nmi_watchdog_type. I > didn't want to add it in this patchset as I think that a single parameter > can handle the enablement and type of the NMI watchdog. > > What do you think? I think it's OK like it is. thanks,
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f2040d4..a8833c7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2577,7 +2577,7 @@ Format: [state][,regs][,debounce][,die] nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels - Format: [panic,][nopanic,][num] + Format: [panic,][nopanic,][num,][hpet] Valid num: 0 or 1 0 - turn hardlockup detector in nmi_watchdog off 1 - turn hardlockup detector in nmi_watchdog on @@ -2587,6 +2587,9 @@ please see 'nowatchdog'. This is useful when you use a panic=... timeout and need the box quickly up again. + When hpet is specified, the NMI watchdog will be driven + by an HPET timer, if available in the system. Otherwise, + the perf-based implementation will be used. These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. diff --git a/kernel/watchdog.c b/kernel/watchdog.c index b94bbe3..b5ce6e4 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -84,7 +84,7 @@ static int __init hardlockup_panic_setup(char *str) nmi_watchdog_user_enabled = 0; else if (!strncmp(str, "1", 1)) nmi_watchdog_user_enabled = 1; - return 1; + return 0; } __setup("nmi_watchdog=", hardlockup_panic_setup); diff --git a/kernel/watchdog_hld_hpet.c b/kernel/watchdog_hld_hpet.c index ebb820d..12e5937 100644 --- a/kernel/watchdog_hld_hpet.c +++ b/kernel/watchdog_hld_hpet.c @@ -17,6 +17,7 @@ #define pr_fmt(fmt) "NMI hpet watchdog: " fmt static struct hpet_hld_data *hld_data; +static bool hardlockup_use_hpet; /** * get_count() - Get the current count of the HPET timer @@ -488,6 +489,15 @@ static void hardlockup_detector_hpet_stop(void) spin_unlock(&hld_data->lock); } +static int __init hardlockup_detector_hpet_setup(char *str) +{ + if (strstr(str, "hpet")) + hardlockup_use_hpet = true; + + return 0; +} +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); + /** * hardlockup_detector_hpet_init() - Initialize the hardlockup detector * @@ -502,6 +512,9 @@ static int __init hardlockup_detector_hpet_init(void) { int ret; + if (!hardlockup_use_hpet) + return -EINVAL; + if (!is_hpet_enabled()) return -ENODEV;
Keep the HPET-based hardlockup detector disabled unless explicitly enabled via a command line argument. If such parameter is not given, the hardlockup detector will fallback to use the perf-based implementation. The function hardlockup_panic_setup() is updated to return 0 in order to to allow __setup functions of specific hardlockup detectors (in this case hardlockup_detector_hpet_setup()) to inspect the nmi_watchdog boot parameter. Cc: Ashok Raj <ashok.raj@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jacob Pan <jacob.jun.pan@intel.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Babu Moger <babu.moger@oracle.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Byungchul Park <byungchul.park@lge.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: "Luis R. Rodriguez" <mcgrof@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Christoffer Dall <cdall@linaro.org> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Kai-Heng Feng <kai.heng.feng@canonical.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: x86@kernel.org Cc: iommu@lists.linux-foundation.org Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> -- checkpatch gives the following warning: CHECK: __setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); This is a false-positive as the option nmi_watchdog is already documented. The option is re-evaluated in this file as well. --- Documentation/admin-guide/kernel-parameters.txt | 5 ++++- kernel/watchdog.c | 2 +- kernel/watchdog_hld_hpet.c | 13 +++++++++++++ 3 files changed, 18 insertions(+), 2 deletions(-)