From: Ingo Molnar <mingo@kernel.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Yu-cheng Yu <yu-cheng.yu@intel.com>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>
Subject: Re: [PATCH v4 0/10] x86/xsaves: Fix XSAVES known issues
Date: Sat, 30 Apr 2016 09:53:44 +0200 [thread overview]
Message-ID: <20160430075343.GA23063@gmail.com> (raw)
In-Reply-To: <5723C6A7.4020704@linux.intel.com>
* Dave Hansen <dave.hansen@linux.intel.com> wrote:
> But I also think it would be pretty nice if 'ls' didn't pay the 2k cost to have
> AVX-512 state if it's not using AVX-512. [...]
A C library might decide to use AVX-512 memset(). RAM is cheap, while allocation
complexity, especially in the kernel, has various other costs.
I mean, we should not worry about per thread allocation sizes that can be compared
to the kernel stack size.
We can still use the compacted area handling instructions, because presumably
those are the fastest and are also the most optimized ones? But I wouldn't use
them to do dynamic allocation: just allocate the maximum possible FPU save area at
task creation time and never again worry about that detail.
Ok?
Thanks,
Ingo
next prev parent reply other threads:[~2016-04-30 7:53 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-04 18:12 [PATCH v4 0/10] x86/xsaves: Fix XSAVES known issues Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 01/10] x86/xsaves: Define and use user_xstate_size for xstate size in signal context Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 02/10] x86/xsaves: Rename xstate_size to kernel_xstate_size to explicitly distinguish xstate size in kernel from user space Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 03/10] x86/xsaves: Keep init_fpstate.xsave.header.xfeatures as zero for init optimization Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 04/10] x86/xsaves: Introduce a new check that allows correct xstates copy from kernel to user directly Yu-cheng Yu
2016-04-29 20:09 ` Dave Hansen
2016-04-29 22:43 ` Yu-cheng Yu
2016-04-30 0:36 ` Dave Hansen
2016-05-02 15:57 ` Yu-cheng Yu
2016-05-02 16:06 ` Dave Hansen
2016-05-02 16:34 ` Yu-cheng Yu
2016-05-02 16:43 ` Dave Hansen
2016-05-02 17:19 ` Yu-cheng Yu
2016-05-02 17:33 ` Dave Hansen
2016-05-02 21:18 ` Yu-cheng Yu
2016-05-02 21:24 ` Yu-cheng Yu
2016-05-02 21:32 ` Dave Hansen
2016-05-02 22:17 ` Yu-cheng Yu
2016-05-02 22:37 ` Dave Hansen
2016-03-04 18:12 ` [PATCH v4 05/10] x86/xsaves: Align xstate components according to CPUID Yu-cheng Yu
2016-04-29 20:11 ` Dave Hansen
2016-03-04 18:12 ` [PATCH v4 06/10] x86/xsaves: Supervisor state component offset Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 07/10] x86/xsaves: Fix PTRACE frames for XSAVES Yu-cheng Yu
2016-04-29 20:16 ` Dave Hansen
2016-04-29 20:38 ` Borislav Petkov
2016-04-29 20:40 ` Dave Hansen
2016-04-29 20:46 ` Borislav Petkov
2016-04-29 20:25 ` Dave Hansen
2016-04-29 22:30 ` Yu-cheng Yu
2016-04-29 22:36 ` Dave Hansen
2016-04-29 22:38 ` Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 08/10] x86/xsaves: Fix XSTATE component offset print out Yu-cheng Yu
2016-04-29 20:26 ` Dave Hansen
2016-03-04 18:12 ` [PATCH v4 09/10] x86/xsaves: Fix xstate_offsets, xstate_sizes for legacy components Yu-cheng Yu
2016-04-29 20:28 ` Dave Hansen
2016-04-29 22:07 ` Yu-cheng Yu
2016-04-29 22:13 ` Dave Hansen
2016-04-29 22:15 ` Yu-cheng Yu
2016-03-04 18:12 ` [PATCH v4 10/10] x86/xsaves: Re-enable XSAVES Yu-cheng Yu
2016-04-29 20:32 ` Dave Hansen
2016-04-29 23:12 ` Yu-cheng Yu
2016-04-30 0:40 ` Dave Hansen
2016-05-02 16:11 ` Yu-cheng Yu
2016-05-04 22:15 ` Dave Hansen
2016-05-04 22:21 ` Yu-cheng Yu
2016-05-04 22:41 ` Dave Hansen
2016-05-04 22:46 ` Yu-cheng Yu
2016-05-04 22:46 ` Dave Hansen
2016-04-29 18:09 ` [PATCH v4 0/10] x86/xsaves: Fix XSAVES known issues Dave Hansen
2016-04-29 19:43 ` Ingo Molnar
2016-04-29 19:57 ` Yu-cheng Yu
2016-04-29 20:03 ` Dave Hansen
2016-04-29 20:07 ` Yu-cheng Yu
2016-04-29 20:25 ` Andy Lutomirski
2016-04-29 20:40 ` Dave Hansen
2016-04-29 20:49 ` Andy Lutomirski
2016-04-29 22:42 ` Dave Hansen
2016-04-30 7:53 ` Ingo Molnar [this message]
2016-05-02 16:28 ` Dave Hansen
2016-05-02 18:32 ` Ingo Molnar
2016-04-29 20:37 ` Dave Hansen
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