From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Alexey Klimov" <aklimov@redhat.com>,
"Amitkumar Karwar" <amitkarwar@gmail.com>,
"Andi Kleen" <ak@linux.intel.com>, "Andrew Lunn" <andrew@lunn.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Gross" <agross@kernel.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Andy Shevchenko" <andy@infradead.org>,
"Anup Patel" <anup.patel@wdc.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 14:15:56 +0100 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Alexey Klimov" <aklimov@redhat.com>,
"Amitkumar Karwar" <amitkarwar@gmail.com>,
"Andi Kleen" <ak@linux.intel.com>, "Andrew Lunn" <andrew@lunn.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Gross" <agross@kernel.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Andy Shevchenko" <andy@infradead.org>,
"Anup Patel" <anup.patel@wdc.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Christoph Hellwig" <hch@lst.de>,
"Christoph Lameter" <cl@linux.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"David Airlie" <airlied@linux.ie>,
"David Laight" <David.Laight@aculab.com>,
"Dennis Zhou" <dennis@kernel.org>,
"Emil Renner Berthing" <kernel@esmil.dk>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Geetha sowjanya" <gakula@marvell.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Guo Ren" <guoren@kernel.org>,
"Hans de Goede" <hdegoede@redhat.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Ian Rogers" <irogers@google.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Jason Wessel" <jason.wessel@windriver.com>,
"Jens Axboe" <axboe@fb.com>, "Jiri Olsa" <jolsa@redhat.com>,
"Joe Perches" <joe@perches.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Kees Cook" <keescook@chromium.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
"Lee Jones" <lee.jones@linaro.org>,
"Marc Zyngier" <maz@kernel.org>,
"Marcin Wojtas" <mw@semihalf.com>,
"Mark Gross" <markgross@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Matti Vaittinen" <mazziesaccount@gmail.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Mike Marciniszyn" <mike.marciniszyn@cornelisnetworks.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Petr Mladek" <pmladek@suse.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Russell King" <linux@armlinux.org.uk>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Solomon Peachy" <pizza@shaftnet.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Stephen Rothwell" <sfr@canb.auug.org.au>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Subbaraya Sundeep" <sbhatta@marvell.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Sunil Goutham" <sgoutham@marvell.com>,
"Tariq Toukan" <tariqt@nvidia.com>, "Tejun Heo" <tj@kernel.org>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Vineet Gupta" <vgupta@kernel.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
bcm-kernel-feedback-list@broadcom.com, kvm@vger.kernel.org,
linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-perf-users@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 14:15:56 +0100 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Alexey Klimov" <aklimov@redhat.com>,
"Amitkumar Karwar" <amitkarwar@gmail.com>,
"Andi Kleen" <ak@linux.intel.com>, "Andrew Lunn" <andrew@lunn.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Gross" <agross@kernel.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Andy Shevchenko" <andy@infradead.org>,
"Anup Patel" <anup.patel@wdc.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Christoph Hellwig" <hch@lst.de>,
"Christoph Lameter" <cl@linux.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"David Airlie" <airlied@linux.ie>,
"David Laight" <David.Laight@aculab.com>,
"Dennis Zhou" <dennis@kernel.org>,
"Emil Renner Berthing" <kernel@esmil.dk>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Geetha sowjanya" <gakula@marvell.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Guo Ren" <guoren@kernel.org>,
"Hans de Goede" <hdegoede@redhat.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Ian Rogers" <irogers@google.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Jason Wessel" <jason.wessel@windriver.com>,
"Jens Axboe" <axboe@fb.com>, "Jiri Olsa" <jolsa@redhat.com>,
"Joe Perches" <joe@perches.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Kees Cook" <keescook@chromium.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
"Lee Jones" <lee.jones@linaro.org>,
"Marc Zyngier" <maz@kernel.org>,
"Marcin Wojtas" <mw@semihalf.com>,
"Mark Gross" <markgross@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Matti Vaittinen" <mazziesaccount@gmail.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Mike Marciniszyn" <mike.marciniszyn@cornelisnetworks.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Petr Mladek" <pmladek@suse.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Russell King" <linux@armlinux.org.uk>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Solomon Peachy" <pizza@shaftnet.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Stephen Rothwell" <sfr@canb.auug.org.au>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Subbaraya Sundeep" <sbhatta@marvell.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Sunil Goutham" <sgoutham@marvell.com>,
"Tariq Toukan" <tariqt@nvidia.com>, "Tejun Heo" <tj@kernel.org>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Vineet Gupta" <vgupta@kernel.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
bcm-kernel-feedback-list@broadcom.com, kvm@vger.kernel.org,
linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-perf-users@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 13:15:56 +0000 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Alexey Klimov" <aklimov@redhat.com>,
"Amitkumar Karwar" <amitkarwar@gmail.com>,
"Andi Kleen" <ak@linux.intel.com>, "Andrew Lunn" <andrew@lunn.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Gross" <agross@kernel.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Andy Shevchenko" <andy@infradead.org>,
"Anup Patel" <anup.patel@wdc.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Christoph Hellwig" <hch@lst.de>,
"Christoph Lameter" <cl@linux.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"David Airlie" <airlied@linux.ie>,
"David Laight" <David.Laight@aculab.com>,
"Dennis Zhou" <dennis@kernel.org>,
"Emil Renner Berthing" <kernel@esmil.dk>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Geetha sowjanya" <gakula@marvell.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Guo Ren" <guoren@kernel.org>,
"Hans de Goede" <hdegoede@redhat.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Ian Rogers" <irogers@google.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Jason Wessel" <jason.wessel@windriver.com>,
"Jens Axboe" <axboe@fb.com>, "Jiri Olsa" <jolsa@redhat.com>,
"Joe Perches" <joe@perches.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Kees Cook" <keescook@chromium.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
"Lee Jones" <lee.jones@linaro.org>,
"Marc Zyngier" <maz@kernel.org>,
"Marcin Wojtas" <mw@semihalf.com>,
"Mark Gross" <markgross@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Matti Vaittinen" <mazziesaccount@gmail.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Mike Marciniszyn" <mike.marciniszyn@cornelisnetworks.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Petr Mladek" <pmladek@suse.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Russell King" <linux@armlinux.org.uk>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Solomon Peachy" <pizza@shaftnet.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Stephen Rothwell" <sfr@canb.auug.org.au>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Subbaraya Sundeep" <sbhatta@marvell.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Sunil Goutham" <sgoutham@marvell.com>,
"Tariq Toukan" <tariqt@nvidia.com>, "Tejun Heo" <tj@kernel.org>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Vineet Gupta" <vgupta@kernel.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
bcm-kernel-feedback-list@broadcom.com, kvm@vger.kernel.org,
linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-perf-users@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 14:15:56 +0100 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Alexey Klimov" <aklimov@redhat.com>,
"Amitkumar Karwar" <amitkarwar@gmail.com>,
"Andi Kleen" <ak@linux.intel.com>, "Andrew Lunn" <andrew@lunn.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Gross" <agross@kernel.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Andy Shevchenko" <andy@infradead.org>,
"Anup Patel" <anup.patel@wdc.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Christoph Hellwig" <hch@lst.de>,
"Christoph Lameter" <cl@linux.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"David Airlie" <airlied@linux.ie>,
"David Laight" <David.Laight@aculab.com>,
"Dennis Zhou" <dennis@kernel.org>,
"Emil Renner Berthing" <kernel@esmil.dk>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Geetha sowjanya" <gakula@marvell.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Guo Ren" <guoren@kernel.org>,
"Hans de Goede" <hdegoede@redhat.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Ian Rogers" <irogers@google.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Jason Wessel" <jason.wessel@windriver.com>,
"Jens Axboe" <axboe@fb.com>, "Jiri Olsa" <jolsa@redhat.com>,
"Joe Perches" <joe@perches.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Kees Cook" <keescook@chromium.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
"Lee Jones" <lee.jones@linaro.org>,
"Marc Zyngier" <maz@kernel.org>,
"Marcin Wojtas" <mw@semihalf.com>,
"Mark Gross" <markgross@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Matti Vaittinen" <mazziesaccount@gmail.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Mike Marciniszyn" <mike.marciniszyn@cornelisnetworks.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Petr Mladek" <pmladek@suse.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Russell King" <linux@armlinux.org.uk>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Solomon Peachy" <pizza@shaftnet.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Stephen Rothwell" <sfr@canb.auug.org.au>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Subbaraya Sundeep" <sbhatta@marvell.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Sunil Goutham" <sgoutham@marvell.com>,
"Tariq Toukan" <tariqt@nvidia.com>, "Tejun Heo" <tj@kernel.org>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Vineet Gupta" <vgupta@kernel.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Will Deacon" <will@kernel.org>,
bcm-kernel-feedback-list@broadcom.com, kvm@vger.kernel.org,
linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-perf-users@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 14:15:56 +0100 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
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WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Yury Norov <yury.norov@gmail.com>
Cc: "Juri Lelli" <juri.lelli@redhat.com>,
"Andrew Lunn" <andrew@lunn.ch>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Guo Ren" <guoren@kernel.org>, "Christoph Lameter" <cl@linux.com>,
"Christoph Hellwig" <hch@lst.de>,
"Andi Kleen" <ak@linux.intel.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Mel Gorman" <mgorman@suse.de>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Petr Mladek" <pmladek@suse.com>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Jens Axboe" <axboe@fb.com>, "Andy Lutomirski" <luto@kernel.org>,
"Lee Jones" <lee.jones@linaro.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
linux-crypto@vger.kernel.org, "Joe Perches" <joe@perches.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Anup Patel" <anup.patel@wdc.com>,
linux-ia64@vger.kernel.org, "David Airlie" <airlied@linux.ie>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Solomon Peachy" <pizza@shaftnet.org>,
"Stephen Rothwell" <sfr@canb.auug.org.au>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
"Dennis Zhou" <dennis@kernel.org>,
"Matti Vaittinen" <mazziesaccount@gmail.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Tejun Heo" <tj@kernel.org>,
linux-arm-kernel@lists.infradead.org,
"Stephen Boyd" <sboyd@kernel.org>,
"Tariq Toukan" <tariqt@nvidia.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Emil Renner Berthing" <kernel@esmil.dk>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Mike Marciniszyn" <mike.marciniszyn@cornelisnetworks.com>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Subbaraya Sundeep" <sbhatta@marvell.com>,
"Will Deacon" <will@kernel.org>,
"Sagi Grimberg" <sagi@grimberg.me>,
linux-csky@vger.kernel.org,
bcm-kernel-feedback-list@broadcom.com,
linux-snps-arc@lists.infradead.org,
"Kees Cook" <keescook@chromium.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Vineet Gupta" <vgupta@kernel.org>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Mark Gross" <markgross@kernel.org>,
"Borislav Petkov" <bp@alien8.de>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"David Laight" <David.Laight@aculab.com>,
linux-alpha@vger.kernel.org,
"Geetha sowjanya" <gakula@marvell.com>,
"Ian Rogers" <irogers@google.com>,
kvm@vger.kernel.org, "Amitkumar Karwar" <amitkarwar@gmail.com>,
linux-mm@kvack.org, linux-riscv@lists.infradead.org,
"Jiri Olsa" <jolsa@redhat.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Marc Zyngier" <maz@kernel.org>,
"Russell King" <linux@armlinux.org.uk>,
"Andy Gross" <agross@kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Sunil Goutham" <sgoutham@marvell.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
linux-s390@vger.kernel.org, "Alexey Klimov" <aklimov@redhat.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Hans de Goede" <hdegoede@redhat.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Marcin Wojtas" <mw@semihalf.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Jason Wessel" <jason.wessel@windriver.com>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Andy Shevchenko" <andy@infradead.org>
Subject: Re: [PATCH 13/17] kernel/cpu: add num_possible_cpus counter
Date: Tue, 21 Dec 2021 14:15:56 +0100 [thread overview]
Message-ID: <YcHTjJxmUntOHKXB@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20211218212014.1315894-14-yury.norov@gmail.com>
On Sat, Dec 18, 2021 at 01:20:09PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_possible_mask is actively used
> in the kernel. This patch adds a counter for possible cpus, so that
> users that call num_possible_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask underlying.
So what user actually cares about performance here enough to warrant
this?
> +EXPORT_SYMBOL(set_cpu_possible);
NAK
next prev parent reply other threads:[~2021-12-21 13:15 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-18 21:19 [PATCH v2 00/17] lib/bitmap: optimize bitmap_weight() usage Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` [PATCH 01/17] all: don't use bitmap_weight() where possible Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 22:15 ` Michał Mirosław
2021-12-18 22:15 ` Michał Mirosław
2021-12-18 22:15 ` Michał Mirosław
2021-12-18 22:15 ` Michał Mirosław
2021-12-18 22:15 ` Michał Mirosław
2021-12-18 23:28 ` Yury Norov
2021-12-18 23:28 ` Yury Norov
2021-12-18 23:28 ` Yury Norov
2021-12-18 23:28 ` Yury Norov
2021-12-18 23:28 ` Yury Norov
2021-12-18 23:28 ` Yury Norov
2021-12-18 21:19 ` [PATCH 02/17] drivers: rename num_*_cpus variables Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` [PATCH 03/17] fix open-coded for_each_set_bit() Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:19 ` Yury Norov
2021-12-18 21:20 ` [PATCH 04/17] all: replace bitmap_weight with bitmap_empty where appropriate Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 05/17] all: replace cpumask_weight with cpumask_empty " Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 06/17] all: replace nodes_weight with nodes_empty " Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 07/17] lib/bitmap: add bitmap_weight_{cmp,eq,gt,ge,lt,le} functions Yury Norov
2021-12-18 21:20 ` [PATCH 07/17] lib/bitmap: add bitmap_weight_{cmp, eq, gt, ge, lt, le} functions Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 07/17] lib/bitmap: add bitmap_weight_{cmp,eq,gt,ge,lt,le} functions Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 08/17] all: replace bitmap_weight with bitmap_weight_{eq,gt,ge,lt,le} where appropriate Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 08/17] all: replace bitmap_weight with bitmap_weight_{eq, gt, ge, lt, le} " Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 08/17] all: replace bitmap_weight with bitmap_weight_{eq,gt,ge,lt,le} " Yury Norov
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-20 16:41 ` Greg Kroah-Hartman
2021-12-18 21:20 ` [PATCH 09/17] lib/cpumask: add cpumask_weight_{eq,gt,ge,lt,le} Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 10/17] lib/nodemask: add nodemask_weight_{eq,gt,ge,lt,le} Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 11/17] lib/nodemask: add num_node_state_eq() Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 12/17] kernel/cpu.c: fix init_cpu_online Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 13/17] kernel/cpu: add num_possible_cpus counter Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-21 13:15 ` Peter Zijlstra [this message]
2021-12-21 13:15 ` Peter Zijlstra
2021-12-21 13:15 ` Peter Zijlstra
2021-12-21 13:15 ` Peter Zijlstra
2021-12-21 13:15 ` Peter Zijlstra
2021-12-21 13:15 ` Peter Zijlstra
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 14/17] kernel/cpu: add num_present_cpu counter Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-21 13:14 ` Peter Zijlstra
2021-12-21 13:14 ` Peter Zijlstra
2021-12-21 13:14 ` Peter Zijlstra
2021-12-21 13:14 ` Peter Zijlstra
2021-12-21 13:14 ` Peter Zijlstra
2021-12-21 13:14 ` Peter Zijlstra
2021-12-18 21:20 ` [PATCH 15/17] kernel/cpu: add num_active_cpu counter Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-21 13:13 ` Peter Zijlstra
2021-12-21 13:13 ` Peter Zijlstra
2021-12-21 13:13 ` Peter Zijlstra
2021-12-21 13:13 ` Peter Zijlstra
2021-12-21 13:13 ` Peter Zijlstra
2021-12-21 13:13 ` Peter Zijlstra
2021-12-18 21:20 ` [PATCH 16/17] tools/bitmap: sync bitmap_weight Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` [PATCH 17/17] MAINTAINERS: add cpumask and nodemask files to BITMAP_API Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
2021-12-18 21:20 ` Yury Norov
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