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Message-ID: <ZwW7E2gSUM8SHAzo@fan> Date: Tue, 8 Oct 2024 16:06:59 -0700 From: Fan Ni <nifan.cxl@...il.com> To: ira.weiny@...el.com Cc: Ira Weiny <ira.weiny@...el.com>, Dave Jiang <dave.jiang@...el.com>, Jonathan Cameron <Jonathan.Cameron@...wei.com>, Navneet Singh <navneet.singh@...el.com>, Jonathan Corbet <corbet@....net>, Andrew Morton <akpm@...ux-foundation.org>, Dan Williams <dan.j.williams@...el.com>, Davidlohr Bueso <dave@...olabs.net>, Alison Schofield <alison.schofield@...el.com>, Vishal Verma <vishal.l.verma@...el.com>, linux-btrfs@...r.kernel.org, linux-cxl@...r.kernel.org, linux-doc@...r.kernel.org, nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Rasmus Villemoes <linux@...musvillemoes.dk>, Sergey Senozhatsky <senozhatsky@...omium.org>, Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>, Johannes Thumshirn <johannes.thumshirn@....com>, "Li, Ming" <ming4.li@...el.com>, Robert Moore <robert.moore@...el.com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org, acpica-devel@...ts.linux.dev Subject: Re: [PATCH v4 00/28] DCD: Add support for Dynamic Capacity Devices (DCD) On Tue, Oct 08, 2024 at 03:57:13PM -0700, Fan Ni wrote: > On Mon, Oct 07, 2024 at 06:16:06PM -0500, Ira Weiny wrote: > > A git tree of this series can be found here: > > > > https://github.com/weiny2/linux-kernel/tree/dcd-v4-2024-10-04 > > > > Series info > > =========== > > > > Hi Ira, > > Based on current DC extent release logic, when the extent to release is > in use (for example, created a dax device), no response (4803h) will be sent. > Should we send a response with empty extent list instead? > > Fan Oh. my bad. 4803h does not allow an empty extent list. Fan > > > > This series has 5 parts: > > > > Patch 1-3: Add %pra printk format for struct range > > Patch 4: Add core range_overlaps() function > > Patch 5-6: CXL clean up/prelim patches > > Patch 7-26: Core DCD support > > Patch 27-28: cxl_test support > > > > Background > > ========== > > > > A Dynamic Capacity Device (DCD) (CXL 3.1 sec 9.13.3) is a CXL memory > > device that allows memory capacity within a region to change > > dynamically without the need for resetting the device, reconfiguring > > HDM decoders, or reconfiguring software DAX regions. > > > > One of the biggest use cases for Dynamic Capacity is to allow hosts to > > share memory dynamically within a data center without increasing the > > per-host attached memory. > > > > The general flow for the addition or removal of memory is to have an > > orchestrator coordinate the use of the memory. Generally there are 5 > > actors in such a system, the Orchestrator, Fabric Manager, the Logical > > device, the Host Kernel, and a Host User. > > > > Typical work flows are shown below. > > > > Orchestrator FM Device Host Kernel Host User > > > > | | | | | > > |-------------- Create region ----------------------->| > > | | | | | > > | | | |<-- Create ---| > > | | | | Region | > > |<------------- Signal done --------------------------| > > | | | | | > > |-- Add ----->|-- Add --->|--- Add --->| | > > | Capacity | Extent | Extent | | > > | | | | | > > | |<- Accept -|<- Accept -| | > > | | Extent | Extent | | > > | | | |<- Create --->| > > | | | | DAX dev |-- Use memory > > | | | | | | > > | | | | | | > > | | | |<- Release ---| <-+ > > | | | | DAX dev | > > | | | | | > > |<------------- Signal done --------------------------| > > | | | | | > > |-- Remove -->|- Release->|- Release ->| | > > | Capacity | Extent | Extent | | > > | | | | | > > | |<- Release-|<- Release -| | > > | | Extent | Extent | | > > | | | | | > > |-- Add ----->|-- Add --->|--- Add --->| | > > | Capacity | Extent | Extent | | > > | | | | | > > | |<- Accept -|<- Accept -| | > > | | Extent | Extent | | > > | | | |<- Create ----| > > | | | | DAX dev |-- Use memory > > | | | | | | > > | | | |<- Release ---| <-+ > > | | | | DAX dev | > > |<------------- Signal done --------------------------| > > | | | | | > > |-- Remove -->|- Release->|- Release ->| | > > | Capacity | Extent | Extent | | > > | | | | | > > | |<- Release-|<- Release -| | > > | | Extent | Extent | | > > | | | | | > > |-- Add ----->|-- Add --->|--- Add --->| | > > | Capacity | Extent | Extent | | > > | | | |<- Create ----| > > | | | | DAX dev |-- Use memory > > | | | | | | > > |-- Remove -->|- Release->|- Release ->| | | > > | Capacity | Extent | Extent | | | > > | | | | | | > > | | | (Release Ignored) | | > > | | | | | | > > | | | |<- Release ---| <-+ > > | | | | DAX dev | > > |<------------- Signal done --------------------------| > > | | | | | > > | |- Release->|- Release ->| | > > | | Extent | Extent | | > > | | | | | > > | |<- Release-|<- Release -| | > > | | Extent | Extent | | > > | | | |<- Destroy ---| > > | | | | Region | > > | | | | | > > > > Implementation > > ============== > > > > The series still requires the creation of regions and DAX devices to be > > closely synchronized with the Orchestrator and Fabric Manager. The host > > kernel will reject extents if a region is not yet created. It also > > ignores extent release if memory is in use (DAX device created). These > > synchronizations are not anticipated to be an issue with real > > applications. > > > > In order to allow for capacity to be added and removed a new concept of > > a sparse DAX region is introduced. A sparse DAX region may have 0 or > > more bytes of available space. The total space depends on the number > > and size of the extents which have been added. > > > > Initially it is anticipated that users of the memory will carefully > > coordinate the surfacing of additional capacity with the creation of DAX > > devices which use that capacity. Therefore, the allocation of the > > memory to DAX devices does not allow for specific associations between > > DAX device and extent. This keeps allocations very similar to existing > > DAX region behavior. > > > > To keep the DAX memory allocation aligned with the existing DAX devices > > which do not have tags extents are not allowed to have tags. Future > > support for tags is planned. > > > > Great care was taken to keep the extent tracking simple. Some xarray's > > needed to be added but extra software objects were kept to a minimum. > > > > Region extents continue to be tracked as sub-devices of the DAX region. > > This ensures that region destruction cleans up all extent allocations > > properly. > > > > Some review tags were kept if a patch did not change. > > > > The major functionality of this series includes: > > > > - Getting the dynamic capacity (DC) configuration information from cxl > > devices > > > > - Configuring the DC partitions reported by hardware > > > > - Enhancing the CXL and DAX regions for dynamic capacity support > > a. Maintain a logical separation between hardware extents and > > software managed region extents. This provides an > > abstraction between the layers and should allow for > > interleaving in the future > > > > - Get hardware extent lists for endpoint decoders upon > > region creation. > > > > - Adjust extent/region memory available on the following events. > > a. Add capacity Events > > b. Release capacity events > > > > - Host response for add capacity > > a. do not accept the extent if: > > If the region does not exist > > or an error occurs realizing the extent > > b. If the region does exist > > realize a DAX region extent with 1:1 mapping (no > > interleave yet) > > c. Support the event more bit by processing a list of extents > > marked with the more bit together before setting up a > > response. > > > > - Host response for remove capacity > > a. If no DAX device references the extent; release the extent > > b. If a reference does exist, ignore the request. > > (Require FM to issue release again.) > > > > - Modify DAX device creation/resize to account for extents within a > > sparse DAX region > > > > - Trace Dynamic Capacity events for debugging > > > > - Add cxl-test infrastructure to allow for faster unit testing > > (See new ndctl branch for cxl-dcd.sh test[1]) > > > > - Only support 0 value extent tags > > > > Fan Ni's upstream of Qemu DCD was used for testing. > > > > Remaining work: > > > > 1) Allow mapping to specific extents (perhaps based on > > label/tag) > > 1a) devise region size reporting based on tags > > 2) Interleave support > > > > Possible additional work depending on requirements: > > > > 1) Accept a new extent which extends (but overlaps) an existing > > extent(s) > > 2) Release extents when DAX devices are released if a release > > was previously seen from the device > > 3) Rework DAX device interfaces, memfd has been explored a bit > > > > [1] https://github.com/weiny2/ndctl/tree/dcd-region2-2024-10-01 > > > > --- > > Major changes in v4: > > - iweiny: rebase to 6.12-rc > > - iweiny: Add qos data to regions > > - Jonathan: Fix up shared region detection > > - Jonathan/jgroves/djbw/iweiny: Ignore 0 value tags > > - iweiny: Change DCD partition sysfs entries to allow for qos class and > > additional parameters per partition > > - Petr/Andy: s/%par/%pra/ > > - Andy: Share logic between printing struct resource and struct range > > - Link to v3: https://patch.msgid.link/20240816-dcd-type2-upstream-v3-0-7c9b96cba6d7@intel.com > > > > --- > > Ira Weiny (14): > > test printk: Add very basic struct resource tests > > printk: Add print format (%pra) for struct range > > cxl/cdat: Use %pra for dpa range outputs > > range: Add range_overlaps() > > dax: Document dax dev range tuple > > cxl/pci: Delay event buffer allocation > > cxl/cdat: Gather DSMAS data for DCD regions > > cxl/region: Refactor common create region code > > cxl/events: Split event msgnum configuration from irq setup > > cxl/pci: Factor out interrupt policy check > > cxl/core: Return endpoint decoder information from region search > > dax/bus: Factor out dev dax resize logic > > tools/testing/cxl: Make event logs dynamic > > tools/testing/cxl: Add DC Regions to mock mem data > > > > Navneet Singh (14): > > cxl/mbox: Flag support for Dynamic Capacity Devices (DCD) > > cxl/mem: Read dynamic capacity configuration from the device > > cxl/core: Separate region mode from decoder mode > > cxl/region: Add dynamic capacity decoder and region modes > > cxl/hdm: Add dynamic capacity size support to endpoint decoders > > cxl/mem: Expose DCD partition capabilities in sysfs > > cxl/port: Add endpoint decoder DC mode support to sysfs > > cxl/region: Add sparse DAX region support > > cxl/mem: Configure dynamic capacity interrupts > > cxl/extent: Process DCD events and realize region extents > > cxl/region/extent: Expose region extent information in sysfs > > dax/region: Create resources on sparse DAX regions > > cxl/region: Read existing extents on region creation > > cxl/mem: Trace Dynamic capacity Event Record > > > > Documentation/ABI/testing/sysfs-bus-cxl | 120 +++- > > Documentation/core-api/printk-formats.rst | 13 + > > drivers/cxl/core/Makefile | 2 +- > > drivers/cxl/core/cdat.c | 52 +- > > drivers/cxl/core/core.h | 33 +- > > drivers/cxl/core/extent.c | 486 +++++++++++++++ > > drivers/cxl/core/hdm.c | 213 ++++++- > > drivers/cxl/core/mbox.c | 605 ++++++++++++++++++- > > drivers/cxl/core/memdev.c | 130 +++- > > drivers/cxl/core/port.c | 13 +- > > drivers/cxl/core/region.c | 170 ++++-- > > drivers/cxl/core/trace.h | 65 ++ > > drivers/cxl/cxl.h | 122 +++- > > drivers/cxl/cxlmem.h | 131 +++- > > drivers/cxl/pci.c | 123 +++- > > drivers/dax/bus.c | 352 +++++++++-- > > drivers/dax/bus.h | 4 +- > > drivers/dax/cxl.c | 72 ++- > > drivers/dax/dax-private.h | 47 +- > > drivers/dax/hmem/hmem.c | 2 +- > > drivers/dax/pmem.c | 2 +- > > fs/btrfs/ordered-data.c | 10 +- > > include/acpi/actbl1.h | 2 + > > include/cxl/event.h | 32 + > > include/linux/range.h | 7 + > > lib/test_printf.c | 70 +++ > > lib/vsprintf.c | 55 +- > > tools/testing/cxl/Kbuild | 3 +- > > tools/testing/cxl/test/mem.c | 960 ++++++++++++++++++++++++++---- > > 29 files changed, 3576 insertions(+), 320 deletions(-) > > --- > > base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc > > change-id: 20230604-dcd-type2-upstream-0cd15f6216fd > > > > Best regards, > > -- > > Ira Weiny <ira.weiny@...el.com> > > > > -- > Fan Ni -- Fan Ni
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