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charset=us-ascii Content-Disposition: inline In-Reply-To: <20250115134207.00002918@huawei.com> X-CM-TRANSID:AQAAfwCHGyUhi1NoH8BXAA--.8826S2 X-CM-SenderInfo: 5zdqw5pxtxt0arstlqxsk13x1xpou0fpof0/1tbiAQAFAWhRxgsBrAAqs2 X-Coremail-Antispam: 1Uk129KBjvAXoWfJFW5Jr17KrW8Cw47Gw1Dtrb_yoW8GryDZo WrCwsFqa18Kr1UZF1qywnrXry3X34UuFn8JrZFyw18tFyYqay7Aw1xAw13JanIyry8Crs5 C347tas8CwsrW3Z7n29KB7ZKAUJUUUU5529EdanIXcx71UUUUU7KY7ZEXasCq-sGcSsGvf J3UbIjqfuFe4nvWSU8nxnvy29KBjDU0xBIdaVrnUUvcSsGvfC2KfnxnUUI43ZEXa7xR_UU UUUUUUU== X-Rspam-User: X-Rspamd-Queue-Id: 7E4934000B X-Rspamd-Server: rspam10 X-Stat-Signature: 18pfkiqjw3fwxyhf6ad8qc8yqzrqoodk X-HE-Tag: 1750305605-82814 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 15, 2025 at 01:42:07PM +0000, Jonathan Cameron wrote: > On Fri, 3 Jan 2025 10:57:22 +0530 > Neeraj Kumar wrote: > > > On 27/11/24 04:34PM, Jonathan Cameron wrote: > > >On Thu, 21 Nov 2024 10:18:41 +0000 > > >Jonathan Cameron wrote: > > > > > >> The CXL specification release 3.2 is now available under a click through at > > >> https://computeexpresslink.org/cxl-specification/ and it brings new > > >> shiny toys. > > > > > >If anyone wants to play, basic emulation on my CXL QEMU staging tree > > >https://gitlab.com/jic23/qemu/-/commit/e89b35d264c1bcc04807e7afab1254f35ffc8cb9 > > > > > >Branch with a few other things on top is: > > >https://gitlab.com/jic23/qemu/-/commits/cxl-2024-11-27 > > > > > >Note that this currently doesn't produce real data. I have a plan > > >/ initial PoC / hack to hook that up via an addition to the QEMU cache > > >plugin and an external tool to emulate the hotness tracker counting > > >hardware. Will be a little while before I get that finished, so in > > >a meantime the above exercises the driver. > > > > > >Jonathan > > > > > >> > > >> RFC reason > > >> - Whilst trace capture with a particular configuration is potentially useful > > >> the intent is that CXL HMU units will be used to drive various forms of > > >> hotpage migration for memory tiering setups. This driver doesn't do this > > >> (yet), but rather provides data capture etc for experimentation and > > >> for working out how to mostly put the allocations in the right place to > > >> start with by tuning applications. > > >> > > >> CXL r3.2 introduces a CXL Hotness Monitoring Unit definition. The intent > > >> of this is to provide a way to establish which units of memory (typically > > >> pages or larger) in CXL attached memory are hot. The implementation details > > >> and algorithm are all implementation defined. The specification simply > > >> describes the 'interface' which takes the form of ring buffer of hotness > > >> records in a PCI BAR and defined capability, configuration and status > > >> registers. > > >> > > >> The hardware may have constraints on what it can track, granularity etc > > >> and on how accurately it tracks (e.g. counter exhaustion, inaccurate > > >> trackers). Some of these constraints are discoverable from the hardware > > >> registers, others such as loss of accuracy have no universally accepted > > >> measures as they are typically access pattern dependent. Sadly it is > > >> very unlikely any hardware will implement a truly precise tracker given > > >> the large resource requirements for tracking at a useful granularity. > > >> > > >> There are two fundamental operation modes: > > >> > > >> * Epoch based. Counters are checked after a period of time (Epoch) and > > >> if over a threshold added to the hotlist. > > >> * Always on. Counters run until a threshold is reached, after that the > > >> hot unit is added to the hotlist and the counter released. > > >> > > >> Counting can be filtered on: > > >> > > >> * Region of CXL DPA space (256MiB per bit in a bitmap). > > >> * Type of access - Trusted and non trusted or non trusted only, R/W/RW > > >> > > >> Sampling can be modified by: > > >> > > >> * Downsampling including potentially randomized downsampling. > > >> > > >> The driver presented here is intended to be useful in its own right but > > >> also to act as the first step of a possible path towards hotness monitoring > > >> based hot page migration. Those steps might look like. > > >> > > >> 1. Gather data - drivers provide telemetry like solutions to get that > > >> data. May be enhanced, for example in this driver by providing the > > >> HPA address rather than DPA Unit Address. Userspace can access enough > > >> information to do this so maybe not. > > >> 2. Userspace algorithm development, possibly combined with userspace > > >> triggered migration by PA. Working out how to use different levels > > >> of constrained hardware resources will be challenging. > > >> 3. Move those algorithms in kernel. Will require generalization across > > >> different hotpage trackers etc. > > >> > > >> So far this driver just gives access to the raw data. I will probably kick > > >> of a longer discussion on how to do adaptive sampling needed to actually > > >> use these units for tiering etc, sometime soon (if no one one else beats > > >> me too it). There is a follow up topic of how to virtualize this stuff > > >> for memory stranding cases (VM gets a fixed mixture of fast and slow > > >> memory and should do it's own tiering). > > >> > > >> More details in the Documentation patch but typical commands are: > > >> > > >> $perf record -a -e cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,\ > > >> hotness_threshold=1024,epoch_multiplier=4,epoch_scale=4,range_base=0,\ > > >> range_size=1024,randomized_downsampling=0,downsampling_factor=32,\ > > >> hotness_granual=12 > > > > Facing issue while executing perf record on x86 emulation environment using following steps > > > > 1. Tried applying CHMU Patch on branch cxl-for-6.13 using b4 utility. As > > base commit is not specified, with minor change able to apply patch. > > Compiled kernel with CONFIG_CXL_HMU > > > > 2. Compiled jic23/cxl-2024-11-27 for x86_64-softmmu > > > > 3. Launched Qemu with following CXL topology along with compiled kernel > > VM="-object memory-backend-ram,id=vmem1,share=on,size=512M \ > > -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \ > > -device cxl-rp,port=0,bus=cxl.1,id=root_port13,chassis=0,slot=2 \ > > -device cxl-type3,bus=root_port13,volatile-memdev=vmem1,id=cxl-vmem1 \ > > -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G,cxl-fmw.0.interleave-granularity=8k" > > > > 4. Created region and onlined this memory. Also run top utility on the newly created > > numa node using numactl -m top > > > > 5. Compiled and installed perf utility in qemu environment, and able to > > see cxl_hmu_mem* entries in perf list > > > > root@QEMUCXL2030mm:~# perf list > > > > cxl_hmu_mem0.0.0/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_hmu_mem0.0.1/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_hmu_mem0.0.2/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_hmu_mem1.0.0/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_hmu_mem1.0.1/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_hmu_mem1.0.2/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw ev> > > cxl_pmu_mem0.0/vid=0..0xffff,edge,mask=0..0xffffffff,.../modifier[Raw event descriptor] > > cxl_pmu_mem0.1/vid=0..0xffff,edge,mask=0..0xffffffff,.../modifier[Raw event descriptor] > > cxl_pmu_mem1.0/vid=0..0xffff,edge,mask=0..0xffffffff,.../modifier[Raw event descriptor] > > cxl_pmu_mem1.1/vid=0..0xffff,edge,mask=0..0xffffffff,.../modifier[Raw event descriptor] > > > > > > 6. Tried running perf command mentioned in Documentation/trace/cxl-hmu.rst > > > > root@QEMUCXL2030mm:/home/cxl/cxl-linux-mainline/tools/perf# perf -v > > perf version 6.12.rc5.gc198a4f4a356 > > root@QEMUCXL2030mm:/home/cxl/cxl-linux-mainline/tools/perf# perf record -a -e cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,hotness_threshold=1024,epoch_multiplier=4,epoch_scale=4,range_base=0,range_size=1024,randomized_downsampling=0,downsampling_factor=32,hotness_granual=12 > > event syntax error: '..ess_granual=12' > > \___ Unrecognized input > > This is probably my mistake when cutting and pasting the example from a terminal. > Add a trailing / and something to run. > > perf record -a -e cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,hotness_threshold=1024,epoch_multiplier=4,epoch_scale=4,range_base=0,range_size=1024,randomized_downsampling=0,downsampling_factor=32,hotness_granual=12/ -- sleep 10 Hi Jonathan, I tried to use this new command but perf shows error. Based on the change of hmu iomap_block size[1], my steps are like below: step1: Create cxl region and online the numa node root@ubuntu-jammy-arm64:~/tools# numactl -H available: 3 nodes (0-2) node 0 cpus: 0 1 node 0 size: 1972 MB node 0 free: 1694 MB node 1 cpus: 2 3 node 1 size: 1942 MB node 1 free: 1690 MB node 2 cpus: node 2 size: 256 MB node 2 free: 256 MB node distances: node 0 1 2 0: 10 20 20 1: 20 10 20 2: 20 20 10 step2: Bind this numa node to run 'ls' root@ubuntu-jammy-arm64:~/tools# numactl -m 2 ls build perf.data ndctl perf root@ubuntu-jammy-arm64:~/tools# numastat node0 node1 node2 numa_hit 109323 141170 77 numa_miss 0 0 0 numa_foreign 0 0 0 interleave_hit 519 591 0 local_node 108810 139591 0 other_node 513 1579 77 step3: Use perf tool root@ubuntu-jammy-arm64:~/tools# perf -v perf version 6.15.rc5.g2c3e6f60f5cf root@ubuntu-jammy-arm64:~/tools# perf list | grep -i hmu cxl_hmu_mem0.0.0/hotness_granual=0..0xffffffff,hotness_threshold=0..0xffffffff,downsampling_factor=0..255,.../modifier[Raw event descriptor] root@ubuntu-jammy-arm64:~/tools# perf record -a -e cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,hotness_threshold=1024,epoperf record -a -e cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,hotness_threshold=1024,epoch_multiplier=4,epoch_scale=4,range_base=0,range_size=1024,randomized_downsampling=0,downsampling_factor=32,hotness_granual=12/ -- sleep 10 Error: cxl_hmu_mem0.0.0/epoch_type=0,access_type=6,hotness_threshold=1024,epoch_multiplier=4,epoch_scale=4,range_base=0,range_size=1024,randomized_downsampling=0,downsampling_factor=32,hotness_granual=12/H: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' [1]:https://lore.kernel.org/linux-cxl/aFNsFI5OKrD0CWR3@phytium.com.cn/T/#u Is something wrong on the CHMU interrupts? > > Jonathan > > > > > > > > > Are there any steps i am missing? > > > > Regards, > > Neeraj > > > > >> > > >> $perf report --dump-raw-traces > > >> > > >> Example output. With a counter_width of 16 (0x10) the least significant > > >> 4 bytes are the counter value and the unit index is bits 16-63. > > >> Here all units are over the threshold and the indexes are 0,1,2 etc. > > >> > > >> . ... CXL_HMU data: size 33512 bytes > > >> Header 0: units: 29c counter_width 10 > > >> Header 1 : deadbeef > > >> 0000000000000283 > > >> 0000000000010364 > > >> 0000000000020366 > > >> 000000000003033c > > >> 0000000000040343 > > >> 00000000000502ff > > >> 000000000006030d > > >> 000000000007031a > > >> > > >> Which will produce a list of hotness entries. > > >> Bits[N-1:0] counter value > > >> Bits[63:N] Unit ID (combine with unit size and DPA base + HDM decoder > > >> config to get to a Host Physical Address) > > >> > > >> Specific RFC questions. > > >> - What should be in the header added to the aux buffer. > > >> Currently just the minimum is provided. Number of records > > >> and the counter width needed to decode them. > > >> - Should we reset the counters when doing sampling "-F X" > > >> If the frequency is higher than the epoch we never see any hot units. > > >> If so, when should we reset them? > > >> > > >> Note testing has been light and on emulation only + as perf tool is > > >> a pain to build on a striped back VM, build testing has all be on > > >> arm64 so far. The driver loads though on both arm64 and x86 so > > >> any problems are likely in the perf tool arch specific code > > >> which is build tested (on wrong machine) > > >> > > >> The QEMU emulation needs some cleanup, but I should be able to post > > >> that shortly to let people actually play with this. There are lots > > >> of open questions there on how 'right' we want the emulation to be > > >> and what counting uarch to emulate. > > >> > > >> Jonathan Cameron (4): > > >> cxl: Register devices for CXL Hotness Monitoring Units (CHMU) > > >> cxl: Hotness Monitoring Unit via a Perf AUX Buffer. > > >> perf: Add support for CXL Hotness Monitoring Units (CHMU) > > >> hwtrace: Document CXL Hotness Monitoring Unit driver > > >> > > >> Documentation/trace/cxl-hmu.rst | 197 +++++++ > > >> Documentation/trace/index.rst | 1 + > > >> drivers/cxl/Kconfig | 6 + > > >> drivers/cxl/Makefile | 3 + > > >> drivers/cxl/core/Makefile | 1 + > > >> drivers/cxl/core/core.h | 1 + > > >> drivers/cxl/core/hmu.c | 64 ++ > > >> drivers/cxl/core/port.c | 2 + > > >> drivers/cxl/core/regs.c | 14 + > > >> drivers/cxl/cxl.h | 5 + > > >> drivers/cxl/cxlpci.h | 1 + > > >> drivers/cxl/hmu.c | 880 ++++++++++++++++++++++++++++ > > >> drivers/cxl/hmu.h | 23 + > > >> drivers/cxl/pci.c | 26 +- > > >> tools/perf/arch/arm/util/auxtrace.c | 58 ++ > > >> tools/perf/arch/x86/util/auxtrace.c | 76 +++ > > >> tools/perf/util/Build | 1 + > > >> tools/perf/util/auxtrace.c | 4 + > > >> tools/perf/util/auxtrace.h | 1 + > > >> tools/perf/util/cxl-hmu.c | 367 ++++++++++++ > > >> tools/perf/util/cxl-hmu.h | 18 + > > >> 21 files changed, 1748 insertions(+), 1 deletion(-) > > >> create mode 100644 Documentation/trace/cxl-hmu.rst > > >> create mode 100644 drivers/cxl/core/hmu.c > > >> create mode 100644 drivers/cxl/hmu.c > > >> create mode 100644 drivers/cxl/hmu.h > > >> create mode 100644 tools/perf/util/cxl-hmu.c > > >> create mode 100644 tools/perf/util/cxl-hmu.h > > >> > > > > > >