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From:   Nadav Amit <nadav.amit@gmail.com>
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Subject: Re: [RFC 0/6] x86: prefetch_page() vDSO call
Date:   Thu, 25 Feb 2021 01:32:56 -0800
In-Reply-To: <64538CCF-AD11-43C2-9632-E054301F9E6D@gmail.com>
Cc:     Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        Hugh Dickins <hughd@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, x86@kernel.org
To:     Peter Zijlstra <peterz@infradead.org>
References: <20210225072910.2811795-1-namit@vmware.com>
 <YDdiZ1SFRrvRPhkR@hirez.programming.kicks-ass.net>
 <64538CCF-AD11-43C2-9632-E054301F9E6D@gmail.com>
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> On Feb 25, 2021, at 12:52 AM, Nadav Amit <nadav.amit@gmail.com> wrote:
>=20
>=20
>=20
>> On Feb 25, 2021, at 12:40 AM, Peter Zijlstra <peterz@infradead.org> =
wrote:
>>=20
>> On Wed, Feb 24, 2021 at 11:29:04PM -0800, Nadav Amit wrote:
>>> From: Nadav Amit <namit@vmware.com>
>>>=20
>>> Just as applications can use prefetch instructions to overlap
>>> computations and memory accesses, applications may want to overlap =
the
>>> page-faults and compute or overlap the I/O accesses that are =
required
>>> for page-faults of different pages.
[
[ snip ]

>> Interesting, but given we've been removing explicit prefetch from =
some
>> parts of the kernel how useful is this in actual use? I'm thinking =
there
>> should at least be a real user and performance numbers with this =
before
>> merging.
>=20
> Can you give me a reference to the =E2=80=9Cremoving explicit prefetch =
from some
> parts of the kernel=E2=80=9D?

Oh. I get it - you mean we remove we remove the use of explicit memory
prefetch from the kernel code. Well, I don=E2=80=99t think it is really =
related,
but yes, performance numbers are needed.


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