On Fri, Jun 26, 2020 at 10:34 AM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > Hi All, > > On Monday, June 22, 2020 3:50:42 PM CEST Rafael J. Wysocki wrote: > > Hi All, > > > > This series is to address the problem with RCU synchronization occurring, > > possibly relatively often, inside of acpi_ex_system_memory_space_handler(), > > when the namespace and interpreter mutexes are held. > > > > Like I said before, I had decided to change the approach used in the previous > > iteration of this series and to allow the unmap operations carried out by > > acpi_ex_system_memory_space_handler() to be deferred in the first place, > > which is done in patches [1-2/4]. > > In the meantime I realized that calling syncrhonize_rcu_expedited() under the > "tables" mutex within ACPICA is not quite a good idea too and that there is no > reason for any users of acpi_os_unmap_memory() in the tree to use the "sync" > variant of unmapping. > > So, unless I'm missing something, acpi_os_unmap_memory() can be changed to > always defer the final unmapping and the only ACPICA change needed to support > that is the addition of the acpi_os_release_unused_mappings() call to get rid > of the unused mappings when leaving the interpreter (module the extra call in > the debug code for consistency). > > So patches [1-2/4] have been changed accordingly. > > > However, it turns out that the "fast-path" mapping is still useful on top of > > the above to reduce the number of ioremap-iounmap cycles for the same address > > range and so it is introduced by patches [3-4/4]. > > Patches [3-4/4] still do what they did, but they have been simplified a bit > after rebasing on top of the new [1-2/4]. > > The below information is still valid, but it applies to the v3, of course. > > > For details, please refer to the patch changelogs. > > > > The series is available from the git branch at > > > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \ > > acpica-osl > > > > for easier testing. > > Also the series have been tested locally. Ok, I'm still trying to get the original reporter to confirm this reduces the execution time for ASL routines with a lot of OpRegion touches. Shall I rebuild that test kernel with these changes, or are the results from the original RFT still interesting?
