ae2328b529
resctrl_cqm_threshold is stored in a hardware specific chunk size, but exposed to user-space as bytes. This means the filesystem parts of resctrl need to know how the hardware counts, to convert the user provided byte value to chunks. The interface between the architecture's resctrl code and the filesystem ought to treat everything as bytes. Change the unit of resctrl_cqm_threshold to bytes. resctrl_arch_rmid_read() still returns its value in chunks, so this needs converting to bytes. As all the users have been touched, rename the variable to resctrl_rmid_realloc_threshold, which describes what the value is for. Neither r->num_rmid nor hw_res->mon_scale are guaranteed to be a power of 2, so the existing code introduces a rounding error from resctrl's theoretical fraction of the cache usage. This behaviour is kept as it ensures the user visible value matches the value read from hardware when the rmid will be reallocated. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Jamie Iles <quic_jiles@quicinc.com> Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Tested-by: Xin Hao <xhao@linux.alibaba.com> Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> Tested-by: Cristian Marussi <cristian.marussi@arm.com> Link: https://lore.kernel.org/r/20220902154829.30399-20-james.morse@arm.com
108 lines
3 KiB
C
108 lines
3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_RESCTRL_H
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#define _ASM_X86_RESCTRL_H
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#ifdef CONFIG_X86_CPU_RESCTRL
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#include <linux/sched.h>
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#include <linux/jump_label.h>
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#define IA32_PQR_ASSOC 0x0c8f
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/**
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* struct resctrl_pqr_state - State cache for the PQR MSR
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* @cur_rmid: The cached Resource Monitoring ID
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* @cur_closid: The cached Class Of Service ID
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* @default_rmid: The user assigned Resource Monitoring ID
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* @default_closid: The user assigned cached Class Of Service ID
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*
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* The upper 32 bits of IA32_PQR_ASSOC contain closid and the
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* lower 10 bits rmid. The update to IA32_PQR_ASSOC always
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* contains both parts, so we need to cache them. This also
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* stores the user configured per cpu CLOSID and RMID.
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*
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* The cache also helps to avoid pointless updates if the value does
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* not change.
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*/
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struct resctrl_pqr_state {
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u32 cur_rmid;
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u32 cur_closid;
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u32 default_rmid;
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u32 default_closid;
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};
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DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
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DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
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DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
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DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
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/*
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* __resctrl_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR
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*
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* Following considerations are made so that this has minimal impact
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* on scheduler hot path:
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* - This will stay as no-op unless we are running on an Intel SKU
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* which supports resource control or monitoring and we enable by
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* mounting the resctrl file system.
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* - Caches the per cpu CLOSid/RMID values and does the MSR write only
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* when a task with a different CLOSid/RMID is scheduled in.
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* - We allocate RMIDs/CLOSids globally in order to keep this as
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* simple as possible.
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* Must be called with preemption disabled.
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*/
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static void __resctrl_sched_in(void)
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{
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struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
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u32 closid = state->default_closid;
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u32 rmid = state->default_rmid;
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u32 tmp;
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/*
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* If this task has a closid/rmid assigned, use it.
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* Else use the closid/rmid assigned to this cpu.
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*/
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if (static_branch_likely(&rdt_alloc_enable_key)) {
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tmp = READ_ONCE(current->closid);
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if (tmp)
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closid = tmp;
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}
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if (static_branch_likely(&rdt_mon_enable_key)) {
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tmp = READ_ONCE(current->rmid);
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if (tmp)
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rmid = tmp;
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}
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if (closid != state->cur_closid || rmid != state->cur_rmid) {
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state->cur_closid = closid;
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state->cur_rmid = rmid;
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wrmsr(IA32_PQR_ASSOC, rmid, closid);
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}
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}
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static inline unsigned int resctrl_arch_round_mon_val(unsigned int val)
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{
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unsigned int scale = boot_cpu_data.x86_cache_occ_scale;
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/* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
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val /= scale;
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return val * scale;
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}
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static inline void resctrl_sched_in(void)
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{
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if (static_branch_likely(&rdt_enable_key))
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__resctrl_sched_in();
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}
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void resctrl_cpu_detect(struct cpuinfo_x86 *c);
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#else
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static inline void resctrl_sched_in(void) {}
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static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {}
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#endif /* CONFIG_X86_CPU_RESCTRL */
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#endif /* _ASM_X86_RESCTRL_H */
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