Date: Tue, 12 Jan 2021 13:26:18 -0800 From: John Baldwin <jhb@FreeBSD.org> To: Konstantin Belousov <kostikbel@gmail.com>, Emmanuel Vadot <manu@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 11d62b6f31ab - main - linuxkpi: add kernel_fpu_begin/kernel_fpu_end Message-ID: <be0ef658-6075-5575-7221-2701208b5812@FreeBSD.org> In-Reply-To: <X/2hR9Hi3Jhf5ZNs@kib.kiev.ua> References: <202101121143.10CBh02x095972@gitrepo.freebsd.org> <X/2hR9Hi3Jhf5ZNs@kib.kiev.ua>
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On 1/12/21 5:16 AM, Konstantin Belousov wrote: > On Tue, Jan 12, 2021 at 11:43:00AM +0000, Emmanuel Vadot wrote: >> The branch main has been updated by manu: >> >> URL: https://cgit.FreeBSD.org/src/commit/?id=11d62b6f31ab4e99df6d0c6c23406b57eaa37f41 >> >> commit 11d62b6f31ab4e99df6d0c6c23406b57eaa37f41 >> Author: Emmanuel Vadot <manu@FreeBSD.org> >> AuthorDate: 2021-01-12 11:02:38 +0000 >> Commit: Emmanuel Vadot <manu@FreeBSD.org> >> CommitDate: 2021-01-12 11:31:00 +0000 >> >> linuxkpi: add kernel_fpu_begin/kernel_fpu_end >> >> With newer AMD GPUs (>=Navi,Renoir) there is FPU context usage in the >> amdgpu driver. >> The `kernel_fpu_begin/end` implementations in drm did not even allow nested >> begin-end blocks. > > Does Linux allow more then one thread to execute kernel_fpu_begin ? I wonder if FPU_KERN_NOCTX is a better fit? https://stackoverflow.com/questions/15934615/calling-kernel-fpu-begin-twice-before-kernel-fpu-end Claims you can't nest, and the body of the functions shown disable preemption which might be a good match for FPU_KERN_NOCTX? Though I'm not sure if Linux permits sleeping while in fpu_kern_begin(). -- John Baldwin
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