From: Kohei Tarumizu <tarumizu.kohei@fujitsu.com>
To: catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: tarumizu.kohei@fujitsu.com
Subject: [PATCH v2 8/8] docs: ABI: Add sysfs documentation interface of hardware prefetch control driver
Date: Fri, 11 Mar 2022 19:19:40 +0900 [thread overview]
Message-ID: <20220311101940.3403607-9-tarumizu.kohei@fujitsu.com> (raw)
In-Reply-To: <20220311101940.3403607-1-tarumizu.kohei@fujitsu.com>
This describes the sysfs interface implemented on the hardware prefetch
control driver.
Signed-off-by: Kohei Tarumizu <tarumizu.kohei@fujitsu.com>
---
.../ABI/testing/sysfs-devices-system-cpu | 89 +++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 61f5676a7429..c1f6aa1322da 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -681,3 +681,92 @@ Description:
(RO) the list of CPUs that are isolated and don't
participate in load balancing. These CPUs are set by
boot parameter "isolcpus=".
+
+What: /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/hardware_prefetcher_enable
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/ip_prefetcher_enable
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/adjacent_cache_line_prefetcher_enable
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/stream_detect_prefetcher_enable
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/stream_detect_prefetcher_strong
+ /sys/devices/system/cpu/cpu*/cache/index[0,2]/prefetch_control/stream_detect_prefetcher_dist
+Date: March 2022
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description: Parameters for CPU's hardware prefetch control
+
+ This sysfs interface provides Hardware Prefetch control
+ attribute file by using implementation defined registers.
+ These files exists in every CPU's cache/index[0,2] directory,
+ and these affect the cache level of the parent index directory.
+ Each attribute file exists depending on kind of processor and
+ cache level.
+
+ *_prefetcher_enable:
+ (RW) control this prefetcher's enablement state.
+ Read returns current status:
+ 0: this prefetcher is disabled
+ 1: this prefetcher is enabled
+
+ stream_detect_prefetcher_strong:
+ (RW) control prefetcher operation's strongness state.
+ Strong prefetch operation is surely executed, if there is
+ no corresponding data in cache.
+ Weak prefetch operation allows the hardware not to execute
+ operation depending on hardware state.
+
+ Read returns current status:
+ 0: prefetch operation is weak
+ 1: prefetch operation is strong
+
+ stream_detect_prefetcher_dist:
+ (RW) control the prefetcher distance value.
+ Read return current prefetcher distance value in bytes
+ or the string "auto".
+
+ Write either a value in byte or the string "auto" to this
+ parameter. If you write a value less than multiples of a
+ specific value, it is rounded up.
+
+ The value 0 and the string "auto" are the same and have
+ a special meaning. This means that instead of setting
+ dist to a user-specified value, it operates using
+ hardware-specific values.
+
+ - Supported processors
+
+ This sysfs interface is available on several processors, x86
+ and ARM64. Currently, the following processors are supported:
+
+ - x86 processor
+ - INTEL_FAM6_BROADWELL_X
+
+ - ARM64 processor
+ - FUJITSU_CPU_PART_A64FX
+
+ - Attribute mapping
+
+ Some Intel processors have MSR 0x1a4. This register has several
+ specifications depending on the model. This interface provides
+ a one-to-one attribute file to control all the tunable
+ parameters the CPU provides of the following.
+
+ - "* Hardware Prefetcher Disable (R/W)"
+ corresponds to the "hardware_prefetcher_enable"
+
+ - "* Adjacent Cache Line Prefetcher Disable (R/W)"
+ corresponds to the "adjacent_cache_line_prefetcher_enable"
+
+ - "* IP Prefetcher Disable (R/W)"
+ corresponds to the "ip_prefetcher_enable"
+
+ The processor A64FX has register IMP_PF_STREAM_DETECT_CTRL_EL0
+ for Hardware Prefetch Control. This attribute maps each
+ specification to the following.
+
+ - "L*PF_DIS": enablement of hardware prefetcher
+ corresponds to the "stream_detect_prefetcher_enable"
+
+ - "L*W": strongness of hardware prefetcher
+ corresponds to the "stream_detect_prefetcher_strong"
+
+ - "L*_DIST": distance of hardware prefetcher
+ corresponds to the "stream_detect_prefetcher_dist"
--
2.27.0
next prev parent reply other threads:[~2022-03-11 10:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 10:19 [PATCH v2 0/8] Add hardware prefetch control driver for arm64 and x86 Kohei Tarumizu
2022-03-11 10:19 ` [PATCH v2 1/8] drivers: base: Add hardware prefetch control core driver Kohei Tarumizu
2022-03-11 10:19 ` [PATCH v2 2/8] drivers: base: Add Kconfig/Makefile to build " Kohei Tarumizu
2022-03-11 10:19 ` [PATCH v2 3/8] arm64: Add hardware prefetch control support for ARM64 Kohei Tarumizu
2022-03-30 22:11 ` Rob Herring
2022-04-04 11:56 ` tarumizu.kohei
2022-03-11 10:19 ` [PATCH v2 4/8] arm64: Add Kconfig/Makefile to build hardware prefetch control driver Kohei Tarumizu
2022-03-11 10:19 ` [PATCH v2 5/8] arm64: Create cache sysfs directory without ACPI PPTT for hardware prefetch control Kohei Tarumizu
2022-03-30 22:14 ` Rob Herring
2022-04-04 11:48 ` tarumizu.kohei
2022-03-11 10:19 ` [PATCH v2 6/8] x86: Add hardware prefetch control support for x86 Kohei Tarumizu
2022-03-14 21:05 ` Dave Hansen
2022-03-18 6:41 ` tarumizu.kohei
2022-03-11 10:19 ` [PATCH v2 7/8] x86: Add Kconfig/Makefile to build hardware prefetch control driver Kohei Tarumizu
2022-03-11 10:19 ` Kohei Tarumizu [this message]
2022-03-14 16:39 ` [PATCH v2 8/8] docs: ABI: Add sysfs documentation interface of " Jonathan Cameron
2022-03-16 12:56 ` tarumizu.kohei
2022-03-14 19:19 ` [PATCH v2 0/8] Add hardware prefetch control driver for arm64 and x86 Dave Hansen
2022-03-18 6:34 ` tarumizu.kohei
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