From: Dan Williams <dan.j.williams@intel.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>,
stable <stable@vger.kernel.org>, Len Brown <lenb@kernel.org>,
Borislav Petkov <bp@alien8.de>, Ira Weiny <ira.weiny@intel.com>,
James Morse <james.morse@arm.com>,
Erik Kaneda <erik.kaneda@intel.com>,
Myron Stowe <myron.stowe@redhat.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ACPI <linux-acpi@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [RFT][PATCH] ACPI: OSL: Use rwlock instead of RCU for memory management
Date: Fri, 5 Jun 2020 10:08:53 -0700 [thread overview]
Message-ID: <CAPcyv4hWLKP7fdLhWLn8vxf5rJKvKyU0yLfDs0XMjW-9U9tM-g@mail.gmail.com> (raw)
In-Reply-To: <2643462.teTRrieJB7@kreacher>
On Fri, Jun 5, 2020 at 7:06 AM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] ACPI: OSL: Use rwlock instead of RCU for memory management
>
> The ACPI OS layer uses RCU to protect the list of ACPI memory
> mappings from being walked while it is updated. Among other
> situations, that list can be walked in non-NMI interrupt context,
> so using a sleeping lock to protect it is not an option.
>
> However, performance issues related to the RCU usage in there
> appear, as described by Dan Williams:
>
> "Recently a performance problem was reported for a process invoking
> a non-trival ASL program. The method call in this case ends up
> repetitively triggering a call path like:
>
> acpi_ex_store
> acpi_ex_store_object_to_node
> acpi_ex_write_data_to_field
> acpi_ex_insert_into_field
> acpi_ex_write_with_update_rule
> acpi_ex_field_datum_io
> acpi_ex_access_region
> acpi_ev_address_space_dispatch
> acpi_ex_system_memory_space_handler
> acpi_os_map_cleanup.part.14
> _synchronize_rcu_expedited.constprop.89
> schedule
>
> The end result of frequent synchronize_rcu_expedited() invocation is
> tiny sub-millisecond spurts of execution where the scheduler freely
> migrates this apparently sleepy task. The overhead of frequent
> scheduler invocation multiplies the execution time by a factor
> of 2-3X."
>
> In order to avoid these issues, replace the RCU in the ACPI OS
> layer by an rwlock.
>
> That rwlock should not be frequently contended, so the performance
> impact of it is not expected to be significant.
>
> Reported-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> Hi Dan,
>
> This is a possible fix for the ACPI OSL RCU-related performance issues, but
> can you please arrange for the testing of it on the affected systems?
Ugh, is it really this simple? I did not realize the read-side is NMI
safe. I'll take a look.
next prev parent reply other threads:[~2020-06-05 17:09 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 23:39 [PATCH v2] ACPI: Drop rcu usage for MMIO mappings Dan Williams
2020-05-13 8:52 ` [ACPI] 5a91d41f89: BUG:sleeping_function_called_from_invalid_context_at_kernel/locking/mutex.c kernel test robot
2020-06-05 13:32 ` [PATCH v2] ACPI: Drop rcu usage for MMIO mappings Rafael J. Wysocki
2020-06-05 16:18 ` Dan Williams
2020-06-05 16:21 ` Rafael J. Wysocki
2020-06-05 16:39 ` Dan Williams
2020-06-05 17:02 ` Rafael J. Wysocki
2020-06-05 14:06 ` [RFT][PATCH] ACPI: OSL: Use rwlock instead of RCU for memory management Rafael J. Wysocki
2020-06-05 17:08 ` Dan Williams [this message]
2020-06-06 6:56 ` Rafael J. Wysocki
2020-06-08 15:33 ` Rafael J. Wysocki
2020-06-08 16:29 ` Rafael J. Wysocki
2020-06-05 19:40 ` Andy Shevchenko
2020-06-06 6:48 ` Rafael J. Wysocki
2020-06-10 12:17 ` [RFT][PATCH 0/3] ACPI: ACPICA / OSL: Avoid unmapping ACPI memory inside of the AML interpreter Rafael J. Wysocki
2020-06-10 12:20 ` [RFT][PATCH 1/3] ACPICA: Defer unmapping of memory used in memory opregions Rafael J. Wysocki
2020-06-10 12:21 ` [RFT][PATCH 2/3] ACPICA: Remove unused memory mappings on interpreter exit Rafael J. Wysocki
2020-06-12 0:12 ` Kaneda, Erik
2020-06-12 12:05 ` Rafael J. Wysocki
2020-06-13 19:28 ` Rafael J. Wysocki
2020-06-15 19:06 ` Dan Williams
2020-06-10 12:22 ` [RFT][PATCH 3/3] ACPI: OSL: Define ACPI_OS_MAP_MEMORY_FAST_PATH() Rafael J. Wysocki
2020-06-13 19:19 ` [RFT][PATCH 0/3] ACPI: ACPICA / OSL: Avoid unmapping ACPI memory inside of the AML interpreter Rafael J. Wysocki
2020-06-22 13:50 ` [RFT][PATCH v2 0/4] " Rafael J. Wysocki
2020-06-22 13:52 ` [RFT][PATCH v2 1/4] ACPICA: Defer unmapping of opregion memory if supported by OS Rafael J. Wysocki
2020-06-22 13:53 ` [RFT][PATCH v2 2/4] ACPI: OSL: Add support for deferred unmapping of ACPI memory Rafael J. Wysocki
2020-06-22 14:56 ` Andy Shevchenko
2020-06-22 15:27 ` Rafael J. Wysocki
2020-06-22 15:46 ` Andy Shevchenko
2020-06-22 14:01 ` [RFT][PATCH v2 3/4] ACPICA: Preserve memory opregion mappings if supported by OS Rafael J. Wysocki
2020-06-26 22:53 ` Kaneda, Erik
2020-06-29 13:02 ` Rafael J. Wysocki
2020-06-22 14:02 ` [RFT][PATCH v2 4/4] ACPI: OSL: Implement acpi_os_map_memory_fast_path() Rafael J. Wysocki
2020-06-26 17:28 ` [RFT][PATCH v3 0/4] ACPI: ACPICA / OSL: Avoid unmapping ACPI memory inside of the AML interpreter Rafael J. Wysocki
2020-06-26 17:31 ` [RFT][PATCH v3 1/4] ACPICA: Take deferred unmapping of memory into account Rafael J. Wysocki
2020-06-26 17:31 ` [RFT][PATCH v3 2/4] ACPI: OSL: Implement deferred unmapping of ACPI memory Rafael J. Wysocki
2020-06-26 17:32 ` [RFT][PATCH v3 3/4] ACPICA: Preserve memory opregion mappings if supported by OS Rafael J. Wysocki
2020-06-26 17:33 ` [RFT][PATCH v3 4/4] ACPI: OSL: Implement acpi_os_map_memory_fast_path() Rafael J. Wysocki
2020-06-26 18:41 ` [RFT][PATCH v3 0/4] ACPI: ACPICA / OSL: Avoid unmapping ACPI memory inside of the AML interpreter Dan Williams
2020-06-28 17:09 ` Rafael J. Wysocki
2020-06-29 20:46 ` Dan Williams
2020-06-30 11:04 ` Rafael J. Wysocki
2020-06-29 16:31 ` [PATCH v4 0/2] " Rafael J. Wysocki
2020-06-29 16:33 ` [PATCH v4 1/2] ACPI: OSL: Implement deferred unmapping of ACPI memory Rafael J. Wysocki
2020-06-29 16:33 ` [PATCH v4 2/2] ACPICA: Preserve memory opregion mappings Rafael J. Wysocki
2020-06-29 20:57 ` Al Stone
2020-06-30 11:44 ` Rafael J. Wysocki
2020-06-30 15:31 ` Al Stone
2020-06-30 15:52 ` Rafael J. Wysocki
2020-06-30 19:57 ` Al Stone
2020-07-16 19:22 ` Verma, Vishal L
2020-07-19 19:14 ` Rafael J. Wysocki
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