From: Reinette Chatre <reinette.chatre@intel.com>
To: James Morse <james.morse@arm.com>, <x86@kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
<shameerali.kolothum.thodi@huawei.com>,
D Scott Phillips OS <scott@os.amperecomputing.com>,
<carl@os.amperecomputing.com>, <lcherian@marvell.com>,
<bobo.shaobowang@huawei.com>, <tan.shaopeng@fujitsu.com>,
<xingxin.hx@openanolis.org>, <baolin.wang@linux.alibaba.com>,
Jamie Iles <quic_jiles@quicinc.com>,
Xin Hao <xhao@linux.alibaba.com>, <peternewman@google.com>
Subject: Re: [PATCH v3 11/19] x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read()
Date: Thu, 27 Apr 2023 16:40:00 -0700 [thread overview]
Message-ID: <28845d8b-cf7a-b5b7-d5ae-1284e33d063c@intel.com> (raw)
In-Reply-To: <24d3616a-7800-ba91-deed-8bcc639ce6ba@arm.com>
Hi James,
On 4/27/2023 7:19 AM, James Morse wrote:
> On 01/04/2023 00:27, Reinette Chatre wrote:
>> On 3/20/2023 10:26 AM, James Morse wrote:
...
>>> #include <linux/module.h>
>>> #include <linux/sizes.h>
>>> #include <linux/slab.h>
>>> @@ -271,7 +272,7 @@ static void smp_call_rmid_read(void *_arg)
>>>
>>> int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,
>>> u32 closid, u32 rmid, enum resctrl_event_id eventid,
>>> - u64 *val)
>>> + u64 *val, int ignored)
>>> {
>>> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>>> struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
>>> @@ -317,9 +318,14 @@ void __check_limbo(struct rdt_domain *d, bool force_free)
>>> u32 idx_limit = resctrl_arch_system_num_rmid_idx();
>>> struct rmid_entry *entry;
>>> u32 idx, cur_idx = 1;
>>> + int arch_mon_ctx;
>>> bool rmid_dirty;
>>> u64 val = 0;
>>>
>>> + arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, QOS_L3_OCCUP_EVENT_ID);
>>> + if (arch_mon_ctx < 0)
>>> + return;
>
>> The vision for this is not clear to me. When I read that context needs to be allocated
>> I expect it to return a pointer to some new context, not an int. What would the
>> "context" consist of?
>
> It might just need a different name.
>
> For MPAM, this is allocating a monitor, which is the hardware that does the counting in
> the cache or the memory controller. The number of monitors is an implementation choice,
> and may not match the number of CLOSID/RMID that are in use. There aren't guaranteed to be
> enough to allocate one for every control or monitor group up front.
>
> The int being returned is the allocated monitor's index. It identifies which monitor needs
> programming to read the provided CLOSID/RMID, and the counter register to read with the value.
I see.
>
> I can allocate memory for an int if you think that is clearer.
> (I was hoping to leave that for whoever needs something bigger than a pointer)
I'd rather not complicate it in this way.
>>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>>> index ff7452f644e4..03e4f41cd336 100644
>>> --- a/include/linux/resctrl.h
>>> +++ b/include/linux/resctrl.h
>>> @@ -233,6 +233,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
>>> * @rmid: rmid of the counter to read.
>>> * @eventid: eventid to read, e.g. L3 occupancy.
>>> * @val: result of the counter read in bytes.
>>> + * @arch_mon_ctx: An allocated context from resctrl_arch_mon_ctx_alloc().
>>> *
>
>> Could this description be expanded to indicate what this context is used for?
>
> Sure,
> "An architecture specific value from resctrl_arch_mon_ctx_alloc(), for MPAM this
> identifies the hardware monitor allocated for this read request".
This helps. Thank you.
Reinette
next prev parent reply other threads:[~2023-04-27 23:40 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 17:26 [PATCH v3 00/19] x86/resctrl: monitored closid+rmid together, separate arch/fs locking James Morse
2023-03-20 17:26 ` [PATCH v3 01/19] x86/resctrl: Track the closid with the rmid James Morse
2023-03-20 17:26 ` [PATCH v3 02/19] x86/resctrl: Access per-rmid structures by index James Morse
2023-03-21 10:57 ` Ilpo Järvinen
2023-03-31 23:19 ` Reinette Chatre
2023-04-24 13:06 ` Peter Newman
2023-05-25 17:32 ` James Morse
2023-03-20 17:26 ` [PATCH v3 03/19] x86/resctrl: Create helper for RMID allocation and mondata dir creation James Morse
2023-03-21 11:05 ` Ilpo Järvinen
2023-03-31 23:20 ` Reinette Chatre
2023-03-20 17:26 ` [PATCH v3 04/19] x86/resctrl: Move rmid allocation out of mkdir_rdt_prepare() James Morse
2023-03-20 17:26 ` [PATCH v3 05/19] x86/resctrl: Allow RMID allocation to be scoped by CLOSID James Morse
2023-03-21 11:29 ` Ilpo Järvinen
2023-03-20 17:26 ` [PATCH v3 06/19] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID James Morse
2023-03-31 23:21 ` Reinette Chatre
2023-04-27 14:09 ` James Morse
2023-03-20 17:26 ` [PATCH v3 07/19] x86/resctrl: Move CLOSID/RMID matching and setting to use helpers James Morse
2023-03-20 17:26 ` [PATCH v3 08/19] x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow James Morse
2023-03-21 13:21 ` Ilpo Järvinen
2023-04-27 14:09 ` James Morse
2023-03-21 15:14 ` Ilpo Järvinen
2023-04-27 14:09 ` James Morse
2023-04-27 14:25 ` Ilpo Järvinen
2023-05-25 17:32 ` James Morse
2023-03-31 23:24 ` Reinette Chatre
2023-04-27 14:10 ` James Morse
2023-04-27 23:36 ` Reinette Chatre
2023-05-25 17:32 ` James Morse
2023-03-20 17:26 ` [PATCH v3 09/19] x86/resctrl: Queue mon_event_read() instead of sending an IPI James Morse
2023-03-22 14:07 ` Peter Newman
2023-03-23 9:09 ` Peter Newman
2023-04-27 14:12 ` James Morse
2023-04-27 14:11 ` James Morse
2023-03-31 23:25 ` Reinette Chatre
2023-04-27 14:12 ` James Morse
2023-03-20 17:26 ` [PATCH v3 10/19] x86/resctrl: Allow resctrl_arch_rmid_read() to sleep James Morse
2023-03-31 23:26 ` Reinette Chatre
2023-04-27 14:12 ` James Morse
2023-03-20 17:26 ` [PATCH v3 11/19] x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read() James Morse
2023-03-31 23:27 ` Reinette Chatre
2023-04-27 14:19 ` James Morse
2023-04-27 23:40 ` Reinette Chatre [this message]
2023-05-25 17:31 ` James Morse
2023-03-20 17:26 ` [PATCH v3 12/19] x86/resctrl: Make resctrl_mounted checks explicit James Morse
2023-03-31 23:28 ` Reinette Chatre
2023-04-27 14:19 ` James Morse
2023-04-27 23:37 ` Reinette Chatre
2023-05-25 17:31 ` James Morse
2023-03-20 17:26 ` [PATCH v3 13/19] x86/resctrl: Move alloc/mon static keys into helpers James Morse
2023-03-20 17:26 ` [PATCH v3 14/19] x86/resctrl: Make rdt_enable_key the arch's decision to switch James Morse
2023-03-20 17:26 ` [PATCH v3 15/19] x86/resctrl: Add helpers for system wide mon/alloc capable James Morse
2023-03-31 23:29 ` Reinette Chatre
2023-04-27 14:19 ` James Morse
2023-03-20 17:26 ` [PATCH v3 16/19] x86/resctrl: Add cpu online callback for resctrl work James Morse
2023-03-31 23:29 ` Reinette Chatre
2023-03-20 17:26 ` [PATCH v3 17/19] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu James Morse
2023-03-21 15:12 ` Ilpo Järvinen
2023-03-21 15:25 ` Ilpo Järvinen
2023-04-27 14:20 ` James Morse
2023-03-20 17:26 ` [PATCH v3 18/19] x86/resctrl: Add cpu offline callback for resctrl work James Morse
2023-03-21 15:32 ` Ilpo Järvinen
2023-04-27 14:20 ` James Morse
2023-04-27 14:51 ` Ilpo Järvinen
2023-04-05 23:48 ` Reinette Chatre
2023-04-27 14:20 ` James Morse
2023-03-20 17:26 ` [PATCH v3 19/19] x86/resctrl: Separate arch and fs resctrl locks James Morse
2023-05-23 17:14 ` [PATCH v3 00/19] x86/resctrl: monitored closid+rmid together, separate arch/fs locking Tony Luck
2023-05-25 17:31 ` James Morse
2023-05-25 21:00 ` Tony Luck
2023-05-28 20:52 ` Drew Fustini
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