diff options
Diffstat (limited to 'debian/patches-rt/RISC-V-Probe-misaligned-access-speed-in-parallel.patch')
| -rw-r--r-- | debian/patches-rt/RISC-V-Probe-misaligned-access-speed-in-parallel.patch | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/debian/patches-rt/RISC-V-Probe-misaligned-access-speed-in-parallel.patch b/debian/patches-rt/RISC-V-Probe-misaligned-access-speed-in-parallel.patch deleted file mode 100644 index 78e57b07a..000000000 --- a/debian/patches-rt/RISC-V-Probe-misaligned-access-speed-in-parallel.patch +++ /dev/null @@ -1,197 +0,0 @@ -From: Evan Green <evan@rivosinc.com> -Date: Mon, 6 Nov 2023 14:58:55 -0800 -Subject: [PATCH] RISC-V: Probe misaligned access speed in parallel -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz - -Probing for misaligned access speed takes about 0.06 seconds. On a -system with 64 cores, doing this in smp_callin() means it's done -serially, extending boot time by 3.8 seconds. That's a lot of boot time. - -Instead of measuring each CPU serially, let's do the measurements on -all CPUs in parallel. If we disable preemption on all CPUs, the -jiffies stop ticking, so we can do this in stages of 1) everybody -except core 0, then 2) core 0. The allocations are all done outside of -on_each_cpu() to avoid calling alloc_pages() with interrupts disabled. - -For hotplugged CPUs that come in after the boot time measurement, -register CPU hotplug callbacks, and do the measurement there. Interrupts -are enabled in those callbacks, so they're fine to do alloc_pages() in. - -[bigeasy: merge the individual patches into the final step.] - -Reported-by: Jisheng Zhang <jszhang@kernel.org> -Closes: https://lore.kernel.org/all/mhng-9359993d-6872-4134-83ce-c97debe1cf9a@palmer-ri-x1c9/T/#mae9b8f40016f9df428829d33360144dc5026bcbf -Fixes: 584ea6564bca ("RISC-V: Probe for unaligned access speed") -Signed-off-by: Evan Green <evan@rivosinc.com> -Link: https://lore.kernel.org/r/20231106225855.3121724-1-evan@rivosinc.com -Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - arch/riscv/include/asm/cpufeature.h | 2 - arch/riscv/kernel/cpufeature.c | 90 ++++++++++++++++++++++++++++++------ - arch/riscv/kernel/smpboot.c | 1 - 3 files changed, 76 insertions(+), 17 deletions(-) - ---- a/arch/riscv/include/asm/cpufeature.h -+++ b/arch/riscv/include/asm/cpufeature.h -@@ -30,6 +30,4 @@ DECLARE_PER_CPU(long, misaligned_access_ - /* Per-cpu ISA extensions. */ - extern struct riscv_isainfo hart_isa[NR_CPUS]; - --void check_unaligned_access(int cpu); -- - #endif ---- a/arch/riscv/kernel/cpufeature.c -+++ b/arch/riscv/kernel/cpufeature.c -@@ -8,6 +8,7 @@ - - #include <linux/acpi.h> - #include <linux/bitmap.h> -+#include <linux/cpuhotplug.h> - #include <linux/ctype.h> - #include <linux/log2.h> - #include <linux/memory.h> -@@ -29,6 +30,7 @@ - - #define MISALIGNED_ACCESS_JIFFIES_LG2 1 - #define MISALIGNED_BUFFER_SIZE 0x4000 -+#define MISALIGNED_BUFFER_ORDER get_order(MISALIGNED_BUFFER_SIZE) - #define MISALIGNED_COPY_SIZE ((MISALIGNED_BUFFER_SIZE / 2) - 0x80) - - unsigned long elf_hwcap __read_mostly; -@@ -556,24 +558,19 @@ unsigned long riscv_get_elf_hwcap(void) - return hwcap; - } - --void check_unaligned_access(int cpu) -+static int check_unaligned_access(void *param) - { -+ int cpu = smp_processor_id(); - u64 start_cycles, end_cycles; - u64 word_cycles; - u64 byte_cycles; - int ratio; - unsigned long start_jiffies, now; -- struct page *page; -+ struct page *page = param; - void *dst; - void *src; - long speed = RISCV_HWPROBE_MISALIGNED_SLOW; - -- page = alloc_pages(GFP_NOWAIT, get_order(MISALIGNED_BUFFER_SIZE)); -- if (!page) { -- pr_warn("Can't alloc pages to measure memcpy performance"); -- return; -- } -- - /* Make an unaligned destination buffer. */ - dst = (void *)((unsigned long)page_address(page) | 0x1); - /* Unalign src as well, but differently (off by 1 + 2 = 3). */ -@@ -626,7 +623,7 @@ void check_unaligned_access(int cpu) - pr_warn("cpu%d: rdtime lacks granularity needed to measure unaligned access speed\n", - cpu); - -- goto out; -+ return 0; - } - - if (word_cycles < byte_cycles) -@@ -640,18 +637,83 @@ void check_unaligned_access(int cpu) - (speed == RISCV_HWPROBE_MISALIGNED_FAST) ? "fast" : "slow"); - - per_cpu(misaligned_access_speed, cpu) = speed; -+ return 0; -+} - --out: -- __free_pages(page, get_order(MISALIGNED_BUFFER_SIZE)); -+static void check_unaligned_access_nonboot_cpu(void *param) -+{ -+ unsigned int cpu = smp_processor_id(); -+ struct page **pages = param; -+ -+ if (smp_processor_id() != 0) -+ check_unaligned_access(pages[cpu]); -+} -+ -+static int riscv_online_cpu(unsigned int cpu) -+{ -+ static struct page *buf; -+ -+ /* We are already set since the last check */ -+ if (per_cpu(misaligned_access_speed, cpu) != RISCV_HWPROBE_MISALIGNED_UNKNOWN) -+ return 0; -+ -+ buf = alloc_pages(GFP_KERNEL, MISALIGNED_BUFFER_ORDER); -+ if (!buf) { -+ pr_warn("Allocation failure, not measuring misaligned performance\n"); -+ return -ENOMEM; -+ } -+ -+ check_unaligned_access(buf); -+ __free_pages(buf, MISALIGNED_BUFFER_ORDER); -+ return 0; - } - --static int check_unaligned_access_boot_cpu(void) -+/* Measure unaligned access on all CPUs present at boot in parallel. */ -+static int check_unaligned_access_all_cpus(void) - { -- check_unaligned_access(0); -+ unsigned int cpu; -+ unsigned int cpu_count = num_possible_cpus(); -+ struct page **bufs = kzalloc(cpu_count * sizeof(struct page *), -+ GFP_KERNEL); -+ -+ if (!bufs) { -+ pr_warn("Allocation failure, not measuring misaligned performance\n"); -+ return 0; -+ } -+ -+ /* -+ * Allocate separate buffers for each CPU so there's no fighting over -+ * cache lines. -+ */ -+ for_each_cpu(cpu, cpu_online_mask) { -+ bufs[cpu] = alloc_pages(GFP_KERNEL, MISALIGNED_BUFFER_ORDER); -+ if (!bufs[cpu]) { -+ pr_warn("Allocation failure, not measuring misaligned performance\n"); -+ goto out; -+ } -+ } -+ -+ /* Check everybody except 0, who stays behind to tend jiffies. */ -+ on_each_cpu(check_unaligned_access_nonboot_cpu, bufs, 1); -+ -+ /* Check core 0. */ -+ smp_call_on_cpu(0, check_unaligned_access, bufs[0], true); -+ -+ /* Setup hotplug callback for any new CPUs that come online. */ -+ cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "riscv:online", -+ riscv_online_cpu, NULL); -+ -+out: -+ for_each_cpu(cpu, cpu_online_mask) { -+ if (bufs[cpu]) -+ __free_pages(bufs[cpu], MISALIGNED_BUFFER_ORDER); -+ } -+ -+ kfree(bufs); - return 0; - } - --arch_initcall(check_unaligned_access_boot_cpu); -+arch_initcall(check_unaligned_access_all_cpus); - - #ifdef CONFIG_RISCV_ALTERNATIVE - /* ---- a/arch/riscv/kernel/smpboot.c -+++ b/arch/riscv/kernel/smpboot.c -@@ -246,7 +246,6 @@ asmlinkage __visible void smp_callin(voi - - numa_add_cpu(curr_cpuid); - set_cpu_online(curr_cpuid, 1); -- check_unaligned_access(curr_cpuid); - - if (has_vector()) { - if (riscv_v_setup_vsize()) |