From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: add architecture specified current_pt_regs
Date: Fri, 19 Feb 2016 10:32:05 +0000 [thread overview]
Message-ID: <20160219103205.GD27062@arm.com> (raw)
In-Reply-To: <CAN1e=SF4iAVZzvs=+rJxmUX_z7KNSwegxWaor3gDfXD-=MAQ4Q@mail.gmail.com>
On Fri, Feb 19, 2016 at 10:30:09AM +0800, Zhi-zhou wrote:
> On Thu, Feb 18, 2016 at 7:58 PM, Catalin Marinas
> <catalin.marinas@arm.com> wrote:
> >
> > On Thu, Feb 18, 2016 at 07:48:35PM +0800, Zhi-zhou Zhang wrote:
> > > From: zhizhou <zhizhou.zh@gmail.com>
> > >
> > > This patch is based on the implementation of arm. The generic
> > > current_pt_regs is implemented with current->stack. It need to access
> > > memory that would be too expensive.
> >
> > Do you have any performance numbers?
>
> I'm using QEMU, so no. Actually this macro isn't heavily used. I just
> think using the generic
> implementation is not very nice. It get task_struct from sp_el0, then
> get stack(which is
> equal to sp_el0) from task_struct. There are two unnecessary memory accesses.
I'd much rather use the generic implementation unless there's a compelling
reason not to. "I think it's not very nice" doesn't really cut it for me!
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Zhi-zhou <zhizhou.zh@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
robin.murphy@arm.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: add architecture specified current_pt_regs
Date: Fri, 19 Feb 2016 10:32:05 +0000 [thread overview]
Message-ID: <20160219103205.GD27062@arm.com> (raw)
In-Reply-To: <CAN1e=SF4iAVZzvs=+rJxmUX_z7KNSwegxWaor3gDfXD-=MAQ4Q@mail.gmail.com>
On Fri, Feb 19, 2016 at 10:30:09AM +0800, Zhi-zhou wrote:
> On Thu, Feb 18, 2016 at 7:58 PM, Catalin Marinas
> <catalin.marinas@arm.com> wrote:
> >
> > On Thu, Feb 18, 2016 at 07:48:35PM +0800, Zhi-zhou Zhang wrote:
> > > From: zhizhou <zhizhou.zh@gmail.com>
> > >
> > > This patch is based on the implementation of arm. The generic
> > > current_pt_regs is implemented with current->stack. It need to access
> > > memory that would be too expensive.
> >
> > Do you have any performance numbers?
>
> I'm using QEMU, so no. Actually this macro isn't heavily used. I just
> think using the generic
> implementation is not very nice. It get task_struct from sp_el0, then
> get stack(which is
> equal to sp_el0) from task_struct. There are two unnecessary memory accesses.
I'd much rather use the generic implementation unless there's a compelling
reason not to. "I think it's not very nice" doesn't really cut it for me!
Will
next prev parent reply other threads:[~2016-02-19 10:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 11:48 [PATCH] arm64: add architecture specified current_pt_regs Zhi-zhou Zhang
2016-02-18 11:48 ` Zhi-zhou Zhang
2016-02-18 11:58 ` Catalin Marinas
2016-02-18 11:58 ` Catalin Marinas
2016-02-19 2:30 ` Zhi-zhou
2016-02-19 2:30 ` Zhi-zhou
2016-02-19 10:32 ` Will Deacon [this message]
2016-02-19 10:32 ` Will Deacon
2016-02-19 12:01 ` Zhizhou Zhang
2016-02-19 12:01 ` Zhizhou Zhang
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