Skip to contentSkip to conversation

riscv: don't probe unaligned access speed if already done

PATCH Applied Jisheng Zhang 3 participants 3 messages Sep 12, 2023 – Nov 6, 2023 RISC-V

lore
Share & tools
lore

Jisheng Zhang

author
#0 lore raw

PATCH 1/1 riscv: don't probe unaligned access speed if already done

If misaligned_access_speed percpu var isn't so called "HWPROBE MISALIGNED UNKNOWN", it means the probe has happened(this is possible for example, hotplug off then hotplug on one cpu), and the percpu var has been set, don't probe again in this case.

Signed-off-by Jisheng Zhang <[email protected]>
---
 arch/riscv/kernel/cpufeature.c | 4 ++++
 1 file changed, 4 insertions(+)
arch/riscv/kernel/cpufeature.c +4 -0
index 1cfbba65d11a..e12cd22755c7 100644
@@ -568,6 +568,10 @@ void check_unaligned_access(int cpu)
 	void *src;
 	long speed = RISCV_HWPROBE_MISALIGNED_SLOW;
 
+	/* We are already set since the last check */
+	if (per_cpu(misaligned_access_speed, cpu) != RISCV_HWPROBE_MISALIGNED_UNKNOWN)
+		return;
+
 	page = alloc_pages(GFP_NOWAIT, get_order(MISALIGNED_BUFFER_SIZE));
 	if (!page) {
 		pr_warn("Can't alloc pages to measure memcpy performance");
Signature · 1 line
2.40.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 6 lines · Jisheng Zhang

If misaligned_access_speed percpu var isn't so called "HWPROBE MISALIGNED UNKNOWN", it means the probe has happened(this is possible for example, hotplug off then hotplug on one cpu), and the percpu var has been set, don't probe again in this case.

Signed-off-by Jisheng Zhang <[email protected]>

Presumably this should grow a

Fixes 584ea6564bca ("RISC-V: Probe for unaligned access speed")

on application.
Patch seems fine to me,

Reviewed-by Conor Dooley <[email protected]>

Thanks,
Conor.

Quoted 22 lines
---
 arch/riscv/kernel/cpufeature.c | 4 ++++
 1 file changed, 4 insertions(+)
arch/riscv/kernel/cpufeature.c +4 -0
index 1cfbba65d11a..e12cd22755c7 100644
@@ -568,6 +568,10 @@ void check_unaligned_access(int cpu)
 	void *src;
 	long speed = RISCV_HWPROBE_MISALIGNED_SLOW;
 
+	/* We are already set since the last check */
+	if (per_cpu(misaligned_access_speed, cpu) != RISCV_HWPROBE_MISALIGNED_UNKNOWN)
+		return;
+
 	page = alloc_pages(GFP_NOWAIT, get_order(MISALIGNED_BUFFER_SIZE));
 	if (!page) {
 		pr_warn("Can't alloc pages to measure memcpy performance");
Signature · 1 line
2.40.1
CI Applied
#2 lore raw
In reply to Jisheng Zhang
This patch was applied to riscv/linux.git (for-next) by Palmer Dabbelt <[email protected]>:

Hello:

This patch was applied to riscv/linux.git (for-next) by Palmer Dabbelt <[email protected]>:

Quoted 8 lines · On Tue, 12 Sep 2023 23:40:40 +0800 you wrote:

If misaligned_access_speed percpu var isn't so called "HWPROBE MISALIGNED UNKNOWN", it means the probe has happened(this is possible for example, hotplug off then hotplug on one cpu), and the percpu var has been set, don't probe again in this case.

Signed-off-by Jisheng Zhang <[email protected]>

[...]

Here is the summary with links:
- riscv: don't probe unaligned access speed if already done

    https://git.kernel.org/riscv/c/c20d36cc2a20

You are awesome, thank you!

Signature · 2 lines
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html