From: Richard Henderson <richard.henderson@linaro.org>
To: "Stefan Hajnoczi" <stefanha@redhat.com>,
"Sohil Mehta" <sohil.mehta@intel.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Alex Bennée" <alex.bennee@linaro.org>
Cc: "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
qemu-devel@nongnu.org, Dave Hansen <dave.hansen@intel.com>,
linux-kselftest@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org, Raj Ashok <ashok.raj@intel.com>,
Jonathan Corbet <corbet@lwn.net>,
the arch/x86 maintainers <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Zeng Guang <guang.zeng@intel.com>,
Gayatri Kammela <gayatri.kammela@intel.com>,
"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Arnd Bergmann <arnd@arndb.de>,
Ramesh Thomas <ramesh.thomas@intel.com>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
Christian Brauner <christian@brauner.io>,
Jens Axboe <axboe@kernel.dk>, Tony Luck <tony.luck@intel.com>,
Linux API <linux-api@vger.kernel.org>,
Randy E Witt <randy.e.witt@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 00/13] x86 User Interrupts support
Date: Fri, 1 Oct 2021 12:41:59 -0400 [thread overview]
Message-ID: <3abdadab-9b7e-7cc0-5ec5-17fa385ce7d4@linaro.org> (raw)
In-Reply-To: <YVc47ohb4nxrBO5h@stefanha-x1.localdomain>
On 10/1/21 12:35 PM, Stefan Hajnoczi wrote:
> QEMU's TCG threads execute translated code. There are events that
> require interrupting these threads. Today a check is performed at the
> start of every translated block. Most of the time the check is false and
> it's a waste of CPU.
>
> User interrupts can eliminate the need for checks by interrupting TCG
> threads when events occur.
We used to use interrupts, and stopped because we need to wait until the guest is in a
stable state. The guest is always in a stable state at the beginning of each TB.
See 378df4b2375.
r~
prev parent reply other threads:[~2021-10-01 16:44 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210913200132.3396598-1-sohil.mehta@intel.com>
[not found] ` <456bf9cf-87b8-4c3d-ac0c-7e392bcf26de@www.fastmail.com>
[not found] ` <YVXmGTo5Uzp44QQq@stefanha-x1.localdomain>
[not found] ` <778d40fe-ad8e-fd7c-4caa-499910bb0925@intel.com>
2021-10-01 16:35 ` [RFC PATCH 00/13] x86 User Interrupts support Stefan Hajnoczi
2021-10-01 16:41 ` Richard Henderson [this message]
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