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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
commitf4cdf7ca9a1fdcca413157df19753f388a5a224e (patch)
tree60a31895b2446cd7fa27514e8c2843534a0de0da /tools/perf/util/affinity.c
downloadlinux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz
linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ...
Diffstat (limited to 'tools/perf/util/affinity.c')
-rw-r--r--tools/perf/util/affinity.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/tools/perf/util/affinity.c b/tools/perf/util/affinity.c
new file mode 100644
index 000000000..6c64b5f69
--- /dev/null
+++ b/tools/perf/util/affinity.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Manage affinity to optimize IPIs inside the kernel perf API. */
+#define _GNU_SOURCE 1
+#include <sched.h>
+#include <stdlib.h>
+#include <linux/bitmap.h>
+#include <linux/zalloc.h>
+#include <perf/cpumap.h>
+#include "perf.h"
+#include "cpumap.h"
+#include "affinity.h"
+
+static int get_cpu_set_size(void)
+{
+ int sz = cpu__max_cpu().cpu + 8 - 1;
+ /*
+ * sched_getaffinity doesn't like masks smaller than the kernel.
+ * Hopefully that's big enough.
+ */
+ if (sz < 4096)
+ sz = 4096;
+ return sz / 8;
+}
+
+int affinity__setup(struct affinity *a)
+{
+ int cpu_set_size = get_cpu_set_size();
+
+ a->orig_cpus = bitmap_zalloc(cpu_set_size * 8);
+ if (!a->orig_cpus)
+ return -1;
+ sched_getaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);
+ a->sched_cpus = bitmap_zalloc(cpu_set_size * 8);
+ if (!a->sched_cpus) {
+ zfree(&a->orig_cpus);
+ return -1;
+ }
+ bitmap_zero((unsigned long *)a->sched_cpus, cpu_set_size);
+ a->changed = false;
+ return 0;
+}
+
+/*
+ * perf_event_open does an IPI internally to the target CPU.
+ * It is more efficient to change perf's affinity to the target
+ * CPU and then set up all events on that CPU, so we amortize
+ * CPU communication.
+ */
+void affinity__set(struct affinity *a, int cpu)
+{
+ int cpu_set_size = get_cpu_set_size();
+
+ /*
+ * Return:
+ * - if cpu is -1
+ * - restrict out of bound access to sched_cpus
+ */
+ if (cpu == -1 || ((cpu >= (cpu_set_size * 8))))
+ return;
+
+ a->changed = true;
+ __set_bit(cpu, a->sched_cpus);
+ /*
+ * We ignore errors because affinity is just an optimization.
+ * This could happen for example with isolated CPUs or cpusets.
+ * In this case the IPIs inside the kernel's perf API still work.
+ */
+ sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->sched_cpus);
+ __clear_bit(cpu, a->sched_cpus);
+}
+
+static void __affinity__cleanup(struct affinity *a)
+{
+ int cpu_set_size = get_cpu_set_size();
+
+ if (a->changed)
+ sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);
+ zfree(&a->sched_cpus);
+ zfree(&a->orig_cpus);
+}
+
+void affinity__cleanup(struct affinity *a)
+{
+ if (a != NULL)
+ __affinity__cleanup(a);
+}
+
+void cpu_map__set_affinity(const struct perf_cpu_map *cpumap)
+{
+ int cpu_set_size = get_cpu_set_size();
+ unsigned long *cpuset = bitmap_zalloc(cpu_set_size * 8);
+ struct perf_cpu cpu;
+ unsigned int idx;
+
+ if (!cpuset)
+ return;
+
+ perf_cpu_map__for_each_cpu_skip_any(cpu, idx, cpumap)
+ __set_bit(cpu.cpu, cpuset);
+
+ sched_setaffinity(0, cpu_set_size, (cpu_set_t *)cpuset);
+ zfree(&cpuset);
+}