Messages in this thread | | | Subject | Re: [PATCH v5 00/24] x86/resctrl: Merge the CDP resources | From | Babu Moger <> | Date | Tue, 22 Jun 2021 10:47:06 -0500 |
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James, Thanks for taking care comments.
Tested on AMD box. Everything looks good. Thanks
Tested-by: Babu Moger <babu.moger@amd.com>
On 6/17/21 12:57 PM, James Morse wrote: > Hi folks, > > Changes since v4? Padding in the schemata file, typos and variable name > changes. The schemata file padding is to ensure that if CDP is supported > but not enabled, the file looks like this: > | root@resctrl-cdp-v5:~# cat /sys/fs/resctrl/schemata > | MB:0=100;1=100 > | L3:0=7ff;1=7ff > > Changes are noted in each patch. > ---- > > This series re-folds the resctrl code so the CDP resources (L3CODE et al) > behaviour is all contained in the filesystem parts, with a minimum amount > of arch specific code. > > Arm have some CPU support for dividing caches into portions, and > applying bandwidth limits at various points in the SoC. The collective term > for these features is MPAM: Memory Partitioning and Monitoring. > > MPAM is similar enough to Intel RDT, that it should use the defacto linux > interface: resctrl. This filesystem currently lives under arch/x86, and is > tightly coupled to the architecture. > Ultimately, my plan is to split the existing resctrl code up to have an > arch<->fs abstraction, then move all the bits out to fs/resctrl. From there > MPAM can be wired up. > > x86 might have two resources with cache controls, (L2 and L3) but has > extra copies for CDP: L{2,3}{CODE,DATA}, which are marked as enabled > if CDP is enabled for the corresponding cache. > > MPAM has an equivalent feature to CDP, but its a property of the CPU, > not the cache. Resctrl needs to have x86's odd/even behaviour, as that > its the ABI, but this isn't how the MPAM hardware works. It is entirely > possible that an in-kernel user of MPAM would not be using CDP, whereas > resctrl is. > > Pretending L3CODE and L3DATA are entirely separate resources is a neat > trick, but doing this is specific to x86. > Doing this leaves the arch code in control of various parts of the > filesystem ABI: the resources names, and the way the schemata are parsed. > Allowing this stuff to vary between architectures is bad for user space. > > This series collapses the CODE/DATA resources, moving all the user-visible > resctrl ABI into what becomes the filesystem code. CDP becomes the type of > configuration being applied to a cache. This is done by adding a > struct resctrl_schema to the parts of resctrl that will move to fs. This > holds the arch-code resource that is in use for this schema, along with > other properties like the name, and whether the configuration being applied > is CODE/DATA/BOTH. > > This lets us fold the extra resources out of the arch code so that they > don't need to be duplicated if the equivalent feature to CDP is missing, or > implemented in a different way. > > > The first two patches split the resource and domain structs to have an > arch specific 'hw' portion, and the rest that is visible to resctrl. > Future series massage the resctrl code so there are no accesses to 'hw' > structures in the parts of resctrl that will move to fs, providing helpers > where necessary. > > This series adds temporary scaffolding, which it removes a few patches > later. This is to allow things like the ctrlval arrays and resources to be > merged separately, which should make is easier to bisect. These things > are marked temporary, and should all be gone by the end of the series. > > This series is a little rough around the monitors, would a fake > struct resctrl_schema for the monitors simplify things, or be a source > of bugs? > > A side effect of merging these resources, is their names are no longer printed > in the kernel log at boot. e.g: > | resctrl: L3 allocation detected > | resctrl: MB allocation detected > | resctrl: L3 monitoring detected > would previously have had extra entries for 'L3CODE' and 'L3DATA'. > User-space cannot rely on this to discover CDP support, as the kernel log may > be inaccessible, may have been overwritten by newer messages, and because > parsing the kernel log is a bad idea. > > This series is based on tip/master's commit eb7f1579243, and can be retrieved from: > git://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git mpam/resctrl_merge_cdp/v5 > > v4: https://lore.kernel.org/lkml/20210614200941.12383-1-james.morse@arm.com/ > v3: https://lore.kernel.org/lkml/20210519162424.27654-1-james.morse@arm.com/ > v2: https://lore.kernel.org/lkml/20210312175849.8327-1-james.morse@arm.com/ > v1: https://lore.kernel.org/lkml/20201030161120.227225-1-james.morse@arm.com/ > > Parts were previously posted as an RFC here: > https://lore.kernel.org/lkml/20200214182947.39194-1-james.morse@arm.com/ > > James Morse (24): > x86/resctrl: Split struct rdt_resource > x86/resctrl: Split struct rdt_domain > x86/resctrl: Add a separate schema list for resctrl > x86/resctrl: Pass the schema in info dir's private pointer > x86/resctrl: Label the resources with their configuration type > x86/resctrl: Walk the resctrl schema list instead of an arch list > x86/resctrl: Store the effective num_closid in the schema > x86/resctrl: Add resctrl_arch_get_num_closid() > x86/resctrl: Pass the schema to resctrl filesystem functions > x86/resctrl: Swizzle rdt_resource and resctrl_schema in > pseudo_lock_region > x86/resctrl: Add a helper to read/set the CDP configuration > x86/resctrl: Move the schemata names into struct resctrl_schema > x86/resctrl: Group staged configuration into a separate struct > x86/resctrl: Allow different CODE/DATA configurations to be staged > x86/resctrl: Rename update_domains() resctrl_arch_update_domains() > x86/resctrl: Add a helper to read a closid's configuration > x86/resctrl: Pass configuration type to resctrl_arch_get_config() > x86/resctrl: Make ctrlval arrays the same size > x86/resctrl: Apply offset correction when config is staged > x86/resctrl: Calculate the index from the configuration type > x86/resctrl: Merge the ctrl_val arrays > x86/resctrl: Remove rdt_cdp_peer_get() > x86/resctrl: Expand resctrl_arch_update_domains()'s msr_param range > x86/resctrl: Merge the CDP resources > > arch/x86/kernel/cpu/resctrl/core.c | 276 ++++++------- > arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 164 +++++--- > arch/x86/kernel/cpu/resctrl/internal.h | 232 ++++------- > arch/x86/kernel/cpu/resctrl/monitor.c | 44 ++- > arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 12 +- > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 457 ++++++++++++---------- > include/linux/resctrl.h | 185 +++++++++ > 7 files changed, 776 insertions(+), 594 deletions(-) >
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