[{"id":31915,"web_url":"https://patchwork.libcamera.org/comment/31915/","msgid":"<172981733294.3353069.12626022977390973101@ping.linuxembedded.co.uk>","date":"2024-10-25T00:48:52","subject":"Re: [PATCH v6 1/1] libcamera: add method to set thread affinity","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Harvey Yang (2024-10-24 09:13:53)\n> From: Han-Lin Chen \n> \n> Add method to set thread affinity to Thread class.\n\nAs it stands, this is still adding unused code.\n\nCan't we get 'something' into test/threads.cpp so that at least we know\nthe code is both compiled and /run/ by the CI runs ?\n\nPerhaps even as simple as setting the threadAffinity to CPU 0 and making\nsure that's the CPU the thread is on!?\n\n\n#include // For sched_getcpu()\nint cpu = sched_getcpu();\n\nAnd make sure 'cpu' is the value we expect ?\n\nIt could launch a thread on 'each' CPU for instance? Or even just only\nvalidate it gets tied to CPU 0 ?\n\nAre any specific permissions required to be able to use\nThread::setThreadAffinity()?\n\n\n> Signed-off-by: Han-Lin Chen \n> Co-developed-by: Harvey Yang \n> Signed-off-by: Harvey Yang \n> ---\n> include/libcamera/base/thread.h | 5 ++++\n> src/libcamera/base/thread.cpp | 47 +++++++++++++++++++++++++++++++++\n> 2 files changed, 52 insertions(+)\n> \n> diff --git a/include/libcamera/base/thread.h b/include/libcamera/base/thread.h\n> index 4f33de63d..3209d4f7c 100644\n> --- a/include/libcamera/base/thread.h\n> +++ b/include/libcamera/base/thread.h\n> @@ -15,6 +15,7 @@\n> \n> #include \n> #include \n> +#include \n> #include \n> \n> namespace libcamera {\n> @@ -35,6 +36,8 @@ public:\n> void exit(int code = 0);\n> bool wait(utils::duration duration = utils::duration::max());\n> \n> + int setThreadAffinity(const Span &cpus);\n> +\n> bool isRunning();\n> \n> Signal<> finished;\n> @@ -54,6 +57,8 @@ private:\n> void startThread();\n> void finishThread();\n> \n> + void setThreadAffinityInternal();\n> +\n> void postMessage(std::unique_ptr msg, Object *receiver);\n> void removeMessages(Object *receiver);\n> \n> diff --git a/src/libcamera/base/thread.cpp b/src/libcamera/base/thread.cpp\n> index 8735670b8..f6322fe31 100644\n> --- a/src/libcamera/base/thread.cpp\n> +++ b/src/libcamera/base/thread.cpp\n> @@ -9,6 +9,7 @@\n> \n> #include \n> #include \n> +#include \n> #include \n> #include \n> #include \n> @@ -128,6 +129,8 @@ private:\n> int exitCode_;\n> \n> MessageQueue messages_;\n> +\n> + std::optional cpuset_;\n> };\n> \n> /**\n> @@ -281,6 +284,8 @@ void Thread::startThread()\n> data_->tid_ = syscall(SYS_gettid);\n> currentThreadData = data_;\n> \n> + setThreadAffinityInternal();\n> +\n> run();\n> }\n> \n> @@ -410,6 +415,48 @@ bool Thread::wait(utils::duration duration)\n> return hasFinished;\n> }\n> \n> +/**\n> + * \\brief Set the CPU affinity mask of the thread\n> + * \\param[in] cpus The list of CPU indices that the thread is set affinity to\n> + *\n> + * The CPU indices should be within [0, std::thread::hardware_concurrency()).\n> + * If any index is invalid, this function won't modify the thread affinity and\n> + * will return an error.\n> + *\n> + * \\return 0 if all indices are valid, -EINVAL otherwise\n> + */\n> +int Thread::setThreadAffinity(const Span &cpus)\n> +{\n> + const unsigned int numCpus = std::thread::hardware_concurrency();\n> +\n> + MutexLocker locker(data_->mutex_);\n> + data_->cpuset_ = cpu_set_t();\n> + CPU_ZERO(&data_->cpuset_.value());\n> +\n> + for (const unsigned int &cpu : cpus) {\n> + if (cpu >= numCpus) {\n> + LOG(Thread, Error) << \"Invalid CPU \" << cpu << \"for thread affinity\";\n> + return -EINVAL;\n> + }\n> +\n> + CPU_SET(cpu, &data_->cpuset_.value());\n> + }\n> +\n> + if (data_->running_)\n> + setThreadAffinityInternal();\n> +\n> + return 0;\n> +}\n> +\n> +void Thread::setThreadAffinityInternal()\n> +{\n> + if (!data_->cpuset_)\n> + return;\n> +\n> + const cpu_set_t &cpuset = data_->cpuset_.value();\n> + pthread_setaffinity_np(thread_.native_handle(), sizeof(cpuset), &cpuset);\n> +}\n> +\n> /**\n> * \\brief Check if the thread is running\n> *\n> -- \n> 2.47.0.163.g1226f6d8fa-goog\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 9B325C3220\n\tfor ;\n\tFri, 25 Oct 2024 00:48:59 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 8E67065393;\n\tFri, 25 Oct 2024 02:48:58 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 3CA3360366\n\tfor ;\n\tFri, 25 Oct 2024 02:48:56 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id C47008D4;\n\tFri, 25 Oct 2024 02:47:07 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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Or even just only\n> validate it gets tied to CPU 0 ?\n\nAdded unit tests to set affinity to every available cpu core.\nI'm not sure how to run a function on a thread elegantly, so I ended up\ndeclaring a class derived from Object. Please let me know how to make\nit cleaner.\n\n>\n> Are any specific permissions required to be able to use\n> Thread::setThreadAffinity()?\n\nIIUC, a user can call pthread_setaffinity_np on a thread that it owns.\nThe syscall under the hood is sched_setaffinity, which is already included\nin CrOS' allowed syscalls.\nShould I add this info in the commit message?\n\nBR,\nHarvey\n\n\n\n\n>\n>\n> > Signed-off-by: Han-Lin Chen \n> > Co-developed-by: Harvey Yang \n> > Signed-off-by: Harvey Yang \n> > ---\n> > include/libcamera/base/thread.h | 5 ++++\n> > src/libcamera/base/thread.cpp | 47 +++++++++++++++++++++++++++++++++\n> > 2 files changed, 52 insertions(+)\n> >\n> > diff --git a/include/libcamera/base/thread.h b/include/libcamera/base/thread.h\n> > index 4f33de63d..3209d4f7c 100644\n> > --- a/include/libcamera/base/thread.h\n> > +++ b/include/libcamera/base/thread.h\n> > @@ -15,6 +15,7 @@\n> >\n> > #include \n> > #include \n> > +#include \n> > #include \n> >\n> > namespace libcamera {\n> > @@ -35,6 +36,8 @@ public:\n> > void exit(int code = 0);\n> > bool wait(utils::duration duration = utils::duration::max());\n> >\n> > + int setThreadAffinity(const Span &cpus);\n> > +\n> > bool isRunning();\n> >\n> > Signal<> finished;\n> > @@ -54,6 +57,8 @@ private:\n> > void startThread();\n> > void finishThread();\n> >\n> > + void setThreadAffinityInternal();\n> > +\n> > void postMessage(std::unique_ptr msg, Object *receiver);\n> > void removeMessages(Object *receiver);\n> >\n> > diff --git a/src/libcamera/base/thread.cpp b/src/libcamera/base/thread.cpp\n> > index 8735670b8..f6322fe31 100644\n> > --- a/src/libcamera/base/thread.cpp\n> > +++ b/src/libcamera/base/thread.cpp\n> > @@ -9,6 +9,7 @@\n> >\n> > #include \n> > #include \n> > +#include \n> > #include \n> > #include \n> > #include \n> > @@ -128,6 +129,8 @@ private:\n> > int exitCode_;\n> >\n> > MessageQueue messages_;\n> > +\n> > + std::optional cpuset_;\n> > };\n> >\n> > /**\n> > @@ -281,6 +284,8 @@ void Thread::startThread()\n> > data_->tid_ = syscall(SYS_gettid);\n> > currentThreadData = data_;\n> >\n> > + setThreadAffinityInternal();\n> > +\n> > run();\n> > }\n> >\n> > @@ -410,6 +415,48 @@ bool Thread::wait(utils::duration duration)\n> > return hasFinished;\n> > }\n> >\n> > +/**\n> > + * \\brief Set the CPU affinity mask of the thread\n> > + * \\param[in] cpus The list of CPU indices that the thread is set affinity to\n> > + *\n> > + * The CPU indices should be within [0, std::thread::hardware_concurrency()).\n> > + * If any index is invalid, this function won't modify the thread affinity and\n> > + * will return an error.\n> > + *\n> > + * \\return 0 if all indices are valid, -EINVAL otherwise\n> > + */\n> > +int Thread::setThreadAffinity(const Span &cpus)\n> > +{\n> > + const unsigned int numCpus = std::thread::hardware_concurrency();\n> > +\n> > + MutexLocker locker(data_->mutex_);\n> > + data_->cpuset_ = cpu_set_t();\n> > + CPU_ZERO(&data_->cpuset_.value());\n> > +\n> > + for (const unsigned int &cpu : cpus) {\n> > + if (cpu >= numCpus) {\n> > + LOG(Thread, Error) << \"Invalid CPU \" << cpu << \"for thread affinity\";\n> > + return -EINVAL;\n> > + }\n> > +\n> > + CPU_SET(cpu, &data_->cpuset_.value());\n> > + }\n> > +\n> > + if (data_->running_)\n> > + setThreadAffinityInternal();\n> > +\n> > + return 0;\n> > +}\n> > +\n> > +void Thread::setThreadAffinityInternal()\n> > +{\n> > + if (!data_->cpuset_)\n> > + return;\n> > +\n> > + const cpu_set_t &cpuset = data_->cpuset_.value();\n> > + pthread_setaffinity_np(thread_.native_handle(), sizeof(cpuset), &cpuset);\n> > +}\n> > +\n> > /**\n> > * \\brief Check if the thread is running\n> > *\n> > --\n> > 2.47.0.163.g1226f6d8fa-goog\n> >","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id E4B92C3220\n\tfor ;\n\tTue, 29 Oct 2024 08:59:04 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 92D0A653AA;\n\tTue, 29 Oct 2024 09:59:04 +0100 (CET)","from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com\n\t[IPv6:2a00:1450:4864:20::22c])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 0BFD865399\n\tfor ;\n\tTue, 29 Oct 2024 09:59:03 +0100 (CET)","by mail-lj1-x22c.google.com with SMTP id\n\t38308e7fff4ca-2fb5111747cso47200531fa.2\n\tfor ;\n\tTue, 29 Oct 2024 01:59:03 -0700 (PDT)"],"Authentication-Results":"lancelot.ideasonboard.com; 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