lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 23 Feb 2024 15:47:17 -0600
From: "Moger, Babu" <bmoger@....com>
To: Peter Newman <peternewman@...gle.com>, James Morse <james.morse@....com>
Cc: babu.moger@....com, Reinette Chatre <reinette.chatre@...el.com>,
 corbet@....net, fenghua.yu@...el.com, tglx@...utronix.de, mingo@...hat.com,
 bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 paulmck@...nel.org, rdunlap@...radead.org, tj@...nel.org,
 peterz@...radead.org, yanjiewtw@...il.com, kim.phillips@....com,
 lukas.bulwahn@...il.com, seanjc@...gle.com, jmattson@...gle.com,
 leitao@...ian.org, jpoimboe@...nel.org, rick.p.edgecombe@...el.com,
 kirill.shutemov@...ux.intel.com, jithu.joseph@...el.com,
 kai.huang@...el.com, kan.liang@...ux.intel.com,
 daniel.sneddon@...ux.intel.com, pbonzini@...hat.com, sandipan.das@....com,
 ilpo.jarvinen@...ux.intel.com, maciej.wieczor-retman@...el.com,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, eranian@...gle.com
Subject: Re: [PATCH v2 00/17] x86/resctrl : Support AMD Assignable Bandwidth
 Monitoring Counters (ABMC)


On 2/20/2024 12:11 PM, Peter Newman wrote:
> Hi James,
>
> On Tue, Feb 20, 2024 at 7:21 AM James Morse <james.morse@....com> wrote:
>> On 16/02/2024 20:18, Peter Newman wrote:
>>> On Thu, Feb 8, 2024 at 9:29 AM Moger, Babu <babu.moger@....com> wrote:
>>>> On 2/5/24 16:38, Reinette Chatre wrote:
>>>>> You have made it clear on several occasions that you do not intend to support
>>>>> domain level assignment. That may be ok but the interface you create should
>>>>> not prevent future support of domain level assignment.
>>>>>
>>>>> If my point is not clear, could you please share how this interface is able to
>>>>> support domain level assignment in the future?
>>>>>
>>>>> I am starting to think that we need a file similar to the schemata file
>>>>> for group and domain level monitor configurations.
>>>> Something like this?
>>>>
>>>> By default
>>>> #cat /sys/fs/resctrl/monitor_state
>>>> default:0=total=assign,local=assign;1=total=assign,local=assign
>>>>
>>>> With ABMC,
>>>> #cat /sys/fs/resctrl/monitor_state
>>>> ABMC:0=total=unassign,local=unassign;1=total=unassign,local=unassign
>>> The benefit from all the string parsing in this interface is only
>>> halving the number of monitor_state sysfs writes we'd need compared to
>>> creating a separate file for mbm_local and mbm_total. Given that our
>>> use case is to assign the 32 assignable counters to read the bandwidth
>>> of ~256 monitoring groups, this isn't a substantial gain to help us. I
>>> think you should just focus on providing the necessary control
>>> granularity without trying to consolidate writes in this interface. I
>>> will propose an additional interface below to optimize our use case.
>>>
>>> Whether mbm_total and mbm_local are combined in the group directories
>>> or not, I don't see why you wouldn't just repeat the same file
>>> interface in the domain directories for a user needing finer-grained
>>> controls.
>> I don't follow why this has to be done globally. resctrl allows CLOSID to have different
>> configurations for different purposes between different domains (as long as tasks are
>> pinned to CPUs). It feels a bit odd that these counters can't be considered as per-domain too.
> Assigning to all domains at once would allow us to better parallelize
> the resulting IPIs when we do need to iterate a small set of monitors
> over a large list of groups.

Planning to work on v3 of this series. For now, I will exclude the 
global assignment option from this series.

We can add the global assignment support when we get time to optimize 
assignments at later point.

Thanks

Babu Moger


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ