Messages in this thread Patch in this message | | | From | James Morse <> | Subject | [PATCH v4 08/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid | Date | Thu, 25 May 2023 18:01:53 +0000 |
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MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be used for different control groups.
This means once a CLOSID is allocated, all its monitoring ids may still be dirty, and held in limbo.
Instead of allocating the first free CLOSID, on architectures where CONFIG_RESCTRL_RMID_DEPENDS_ON_COSID is enabled, search closid_num_dirty_rmid[] to find the cleanest CLOSID.
The CLOSID found is returned to closid_alloc() for the free list to be updated.
Signed-off-by: James Morse <james.morse@arm.com> --- arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ arch/x86/kernel/cpu/resctrl/monitor.c | 45 ++++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++--- 3 files changed, 61 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index 23e20f89d2b3..96fb7658ff74 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -557,5 +557,7 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r); void __init thread_throttle_mode_init(void); void __init mbm_config_rftype_init(const char *config); void rdt_staged_configs_clear(void); +bool closid_allocated(unsigned int closid); +int resctrl_find_cleanest_closid(void); #endif /* _ASM_X86_RESCTRL_INTERNAL_H */ diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 1e7fa40ee471..128d4c7206e4 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -379,6 +379,51 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid) return ERR_PTR(-ENOSPC); } +/** + * resctrl_find_cleanest_closid() - Find a CLOSID where all the associated + * RMID are clean, or the CLOSID that has + * the most clean RMID. + * + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated CLOSID + * may not be able to allocate clean RMID. To avoid this the allocator will + * choose the CLOSID with the most clean RMID. + * + * When the CLOSID and RMID are independent numbers, the first free CLOSID will + * be returned. + * + * Call when CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is defined. If not, call + * resctrl_closid_alloc_first_free() instead. + */ +int resctrl_find_cleanest_closid(void) +{ + u32 cleanest_closid = ~0, iter_num_dirty; + int i = 0; + + lockdep_assert_held(&rdtgroup_mutex); + + if (!IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) + return -EIO; + + for (i = 0; i < closids_supported(); i++) { + if (closid_allocated(i)) + continue; + + iter_num_dirty = closid_num_dirty_rmid[i]; + if (iter_num_dirty == 0) + return i; + + if (cleanest_closid == ~0) + cleanest_closid = i; + + if (iter_num_dirty < closid_num_dirty_rmid[cleanest_closid]) + cleanest_closid = i; + } + + if (cleanest_closid == ~0) + return -ENOSPC; + return cleanest_closid; +} + /* * For MPAM the RMID value is not unique, and has to be considered with * the CLOSID. The (CLOSID, RMID) pair is allocated on all domains, which diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 6bf5623f82b4..1120c7700126 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -132,11 +132,20 @@ static void closid_init(void) static int closid_alloc(void) { - u32 closid = ffs(closid_free_map); + u32 closid; + int err; - if (closid == 0) - return -ENOSPC; - closid--; + if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) { + err = resctrl_find_cleanest_closid(); + if (err < 0) + return err; + closid = err; + } else { + closid = ffs(closid_free_map); + if (closid == 0) + return -ENOSPC; + closid--; + } clear_bit(closid, &closid_free_map); return closid; @@ -154,7 +163,7 @@ void closid_free(int closid) * Return: true if @closid is currently associated with a resource group, * false if @closid is free */ -static bool closid_allocated(unsigned int closid) +bool closid_allocated(unsigned int closid) { return !test_bit(closid, &closid_free_map); } -- 2.39.2
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