Messages in this thread Patch in this message | | | Date | Thu, 5 Oct 2023 15:13:42 -0500 | Subject | Re: [PATCH v6 10/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid | From | "Moger, Babu" <> |
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Hi James,
On 9/14/2023 12:21 PM, James Morse wrote: > 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. > > Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> > Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> > Tested-By: Peter Newman <peternewman@google.com> > Signed-off-by: James Morse <james.morse@arm.com> > --- > Changes since v4: > * Dropped stale section from comment > --- > arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ > arch/x86/kernel/cpu/resctrl/monitor.c | 42 ++++++++++++++++++++++++++ > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 +++++++++--- > 3 files changed, 58 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h > index ad6e874d9ed2..f06d3d3e0808 100644 > --- a/arch/x86/kernel/cpu/resctrl/internal.h > +++ b/arch/x86/kernel/cpu/resctrl/internal.h > @@ -558,5 +558,7 @@ 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 0c783301d106..0bbed8c62d42 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -388,6 +388,48 @@ 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. > + */ > +int resctrl_find_cleanest_closid(void) > +{ > + u32 cleanest_closid = ~0, iter_num_dirty;
Just naming num_dirty should have been fine. I will leave it you.
> + 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;
Line before the return looks clean.
* if (cleanest_closid == ~0) + return -ENOSPC; + + return cleanest_closid;
Thanks Babu
> +} > + > /* > * 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 fa449ee0d1a7..1f8f1c417a4b 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); > }
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