From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Len Brown <lenb@kernel.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-pm@vger.kernel.org, Robin Jarry <rjarry@redhat.com>,
Joe Mario <jmario@redhat.com>
Subject: Re: [PATCH v2 5/5] x86/idle: Disable IBRS entering mwait idle and enable it on wakeup
Date: Wed, 21 Jun 2023 10:05:06 -0400 [thread overview]
Message-ID: <dcc515cd-d0cf-5a14-8b48-aa94770e50bd@redhat.com> (raw)
In-Reply-To: <20230621073212.GC2046280@hirez.programming.kicks-ass.net>
On 6/21/23 03:32, Peter Zijlstra wrote:
> On Tue, Jun 20, 2023 at 10:06:25AM -0400, Waiman Long wrote:
>> When a user sets "intel_idle.max_cstate=0", it will disable
>> intel_idle and fall back to acpi_idle instead. The acpi_idle code
>> will then call mwait_idle_with_hints() to enter idle state. So when
>> X86_FEATURE_KERNEL_IBRS is enabled, it is necessary to disable IBRS
>> within mwait_idle_with_hints() when IRQ was disabled to avoid performance
>> degradation on silbing thread running user workload.
> Urgh, no, just no. This is nasty.
OK, will take this out in the next version.
Cheers,
Longman
prev parent reply other threads:[~2023-06-21 14:09 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-20 14:06 [PATCH v2 0/5] x86/speculation: Disable IBRS when idle Waiman Long
2023-06-20 14:06 ` [PATCH v2 1/5] x86/speculation: Provide a debugfs file to dump SPEC_CTRL MSRs Waiman Long
2023-06-21 7:41 ` Peter Zijlstra
2023-06-21 8:24 ` Borislav Petkov
2023-06-21 14:02 ` Waiman Long
2023-06-21 13:47 ` Waiman Long
2023-06-20 14:06 ` [PATCH v2 2/5] x86/idle: Disable IBRS when cpu is offline Waiman Long
2023-06-21 7:23 ` Peter Zijlstra
2023-06-21 13:59 ` Waiman Long
2023-06-21 14:36 ` Peter Zijlstra
2023-06-21 14:44 ` Waiman Long
2023-06-21 14:48 ` Peter Zijlstra
2023-06-21 14:51 ` Waiman Long
2023-06-21 14:54 ` Peter Zijlstra
2023-06-21 15:42 ` Waiman Long
2023-06-20 14:06 ` [PATCH v2 3/5] intel_idle: Sync up the SPEC_CTRL MSR value to x86_spec_ctrl_current Waiman Long
2023-06-21 7:38 ` Peter Zijlstra
2023-06-20 14:06 ` [PATCH v2 4/5] intel_idle: Add no_ibrs module parameter to force disable IBRS Waiman Long
2023-06-21 7:30 ` Peter Zijlstra
2023-06-20 14:06 ` [PATCH v2 5/5] x86/idle: Disable IBRS entering mwait idle and enable it on wakeup Waiman Long
2023-06-21 7:32 ` Peter Zijlstra
2023-06-21 14:05 ` Waiman Long [this message]
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