From: Kajol Jain <kjain@linux.ibm.com> To: will@kernel.org, hao.wu@intel.com, mark.rutland@arm.com Cc: trix@redhat.com, yilun.xu@intel.com, luwei.kang@intel.com, mdf@kernel.org, linux-fpga@vger.kernel.org, maddy@linux.vnet.ibm.com, atrajeev@linux.vnet.ibm.com, kjain@linux.ibm.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, rnsastry@linux.ibm.com Subject: [RFC] fpga: dfl: fme: Fix cpu hotplug code Date: Mon, 28 Jun 2021 12:45:46 +0530 [thread overview] Message-ID: <20210628071546.167088-1-kjain@linux.ibm.com> (raw) Commit 724142f8c42a ("fpga: dfl: fme: add performance reporting support") added performance reporting support for FPGA management engine via perf. It also added cpu hotplug feature but it didn't add pmu migration call in cpu offline function. This can create an issue incase the current designated cpu being used to collect fme pmu data got offline, as based on current code we are not migrating fme pmu to new target cpu. Because of that perf will still try to fetch data from that offline cpu and hence we will not get counter data. Patch fixed this issue by adding pmu_migrate_context call in fme_perf_offline_cpu function. Fixes: 724142f8c42a ("fpga: dfl: fme: add performance reporting support") Signed-off-by: Kajol Jain <kjain@linux.ibm.com> --- drivers/fpga/dfl-fme-perf.c | 4 ++++ 1 file changed, 4 insertions(+) --- - This fix patch is not tested (as I don't have required environment). But issue mentioned in the commit msg can be re-created, by starting any fme_perf event and while its still running, offline current designated cpu pointed by cpumask file. Since current code didn't migrating pmu, perf gonna try getting counts from that offlined cpu and hence we will not get event data. --- diff --git a/drivers/fpga/dfl-fme-perf.c b/drivers/fpga/dfl-fme-perf.c index 4299145ef347..b9a54583e505 100644 --- a/drivers/fpga/dfl-fme-perf.c +++ b/drivers/fpga/dfl-fme-perf.c @@ -953,6 +953,10 @@ static int fme_perf_offline_cpu(unsigned int cpu, struct hlist_node *node) return 0; priv->cpu = target; + + /* Migrate fme_perf pmu events to the new target cpu */ + perf_pmu_migrate_context(&priv->pmu, cpu, target); + return 0; } -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: Kajol Jain <kjain@linux.ibm.com> To: will@kernel.org, hao.wu@intel.com, mark.rutland@arm.com Cc: maddy@linux.vnet.ibm.com, luwei.kang@intel.com, rnsastry@linux.ibm.com, trix@redhat.com, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, atrajeev@linux.vnet.ibm.com, mdf@kernel.org, kjain@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, yilun.xu@intel.com Subject: [RFC] fpga: dfl: fme: Fix cpu hotplug code Date: Mon, 28 Jun 2021 12:45:46 +0530 [thread overview] Message-ID: <20210628071546.167088-1-kjain@linux.ibm.com> (raw) Commit 724142f8c42a ("fpga: dfl: fme: add performance reporting support") added performance reporting support for FPGA management engine via perf. It also added cpu hotplug feature but it didn't add pmu migration call in cpu offline function. This can create an issue incase the current designated cpu being used to collect fme pmu data got offline, as based on current code we are not migrating fme pmu to new target cpu. Because of that perf will still try to fetch data from that offline cpu and hence we will not get counter data. Patch fixed this issue by adding pmu_migrate_context call in fme_perf_offline_cpu function. Fixes: 724142f8c42a ("fpga: dfl: fme: add performance reporting support") Signed-off-by: Kajol Jain <kjain@linux.ibm.com> --- drivers/fpga/dfl-fme-perf.c | 4 ++++ 1 file changed, 4 insertions(+) --- - This fix patch is not tested (as I don't have required environment). But issue mentioned in the commit msg can be re-created, by starting any fme_perf event and while its still running, offline current designated cpu pointed by cpumask file. Since current code didn't migrating pmu, perf gonna try getting counts from that offlined cpu and hence we will not get event data. --- diff --git a/drivers/fpga/dfl-fme-perf.c b/drivers/fpga/dfl-fme-perf.c index 4299145ef347..b9a54583e505 100644 --- a/drivers/fpga/dfl-fme-perf.c +++ b/drivers/fpga/dfl-fme-perf.c @@ -953,6 +953,10 @@ static int fme_perf_offline_cpu(unsigned int cpu, struct hlist_node *node) return 0; priv->cpu = target; + + /* Migrate fme_perf pmu events to the new target cpu */ + perf_pmu_migrate_context(&priv->pmu, cpu, target); + return 0; } -- 2.31.1
next reply other threads:[~2021-06-28 7:18 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-28 7:15 Kajol Jain [this message] 2021-06-28 7:15 ` [RFC] fpga: dfl: fme: Fix cpu hotplug code Kajol Jain 2021-06-28 9:01 ` Xu Yilun 2021-06-28 9:01 ` Xu Yilun 2021-06-28 10:04 ` kajoljain 2021-06-28 10:04 ` kajoljain 2021-06-28 18:40 ` Moritz Fischer 2021-06-28 18:40 ` Moritz Fischer 2021-06-29 7:14 ` kajoljain 2021-06-29 7:14 ` kajoljain
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