From: Borislav Petkov <bp@alien8.de>
To: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Andy Lutomirski <luto@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Michal Hocko <mhocko@kernel.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
Ira Weiny <ira.weiny@intel.com>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH 5/8] x86/clear_page: add clear_page_uncached()
Date: Thu, 15 Oct 2020 12:40:47 +0200 [thread overview]
Message-ID: <20201015104047.GD11838@zn.tnic> (raw)
In-Reply-To: <50286c32-2869-cbd5-b178-0ad0c13584ea@oracle.com>
On Wed, Oct 14, 2020 at 08:21:57PM -0700, Ankur Arora wrote:
> Also, if we did extend clear_page() to take the page-size as parameter
> we still might not have enough information (ex. a 4K or a 2MB page that
> clear_page() sees could be part of a GUP of a much larger extent) to
> decide whether to go uncached or not.
clear_page* assumes 4K. All of the lowlevel asm variants do. So adding
the size there won't bring you a whole lot.
So you'd need to devise this whole thing differently. Perhaps have a
clear_pages() helper which decides based on size what to do: uncached
clearing or the clear_page() as is now in a loop.
Looking at the callsites would give you a better idea I'd say.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-10-15 10:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 8:32 [PATCH 0/8] Use uncached writes while clearing gigantic pages Ankur Arora
2020-10-14 8:32 ` [PATCH 1/8] x86/cpuid: add X86_FEATURE_NT_GOOD Ankur Arora
2020-10-14 8:32 ` [PATCH 2/8] x86/asm: add memset_movnti() Ankur Arora
2020-10-14 8:32 ` [PATCH 3/8] perf bench: " Ankur Arora
2020-10-14 8:32 ` [PATCH 4/8] x86/asm: add clear_page_nt() Ankur Arora
2020-10-14 19:56 ` Borislav Petkov
2020-10-14 21:11 ` Ankur Arora
2020-10-14 8:32 ` [PATCH 5/8] x86/clear_page: add clear_page_uncached() Ankur Arora
2020-10-14 11:10 ` kernel test robot
2020-10-14 11:10 ` kernel test robot
2020-10-14 13:04 ` kernel test robot
2020-10-14 13:04 ` kernel test robot
2020-10-14 15:45 ` Andy Lutomirski
2020-10-14 19:58 ` Borislav Petkov
2020-10-14 21:07 ` Andy Lutomirski
2020-10-14 21:12 ` Borislav Petkov
2020-10-15 3:37 ` Ankur Arora
2020-10-15 10:35 ` Borislav Petkov
2020-10-15 21:20 ` Ankur Arora
2020-10-16 18:21 ` Borislav Petkov
2020-10-15 3:21 ` Ankur Arora
2020-10-15 10:40 ` Borislav Petkov [this message]
2020-10-15 21:40 ` Ankur Arora
2020-10-14 20:54 ` Ankur Arora
2020-10-14 8:32 ` [PATCH 6/8] mm, clear_huge_page: use clear_page_uncached() for gigantic pages Ankur Arora
2020-10-14 15:28 ` Ingo Molnar
2020-10-14 19:15 ` Ankur Arora
2020-10-14 8:32 ` [PATCH 7/8] x86/cpu/intel: enable X86_FEATURE_NT_GOOD on Intel Broadwellx Ankur Arora
2020-10-14 15:31 ` Ingo Molnar
2020-10-14 19:23 ` Ankur Arora
2020-10-14 8:32 ` [PATCH 8/8] x86/cpu/amd: enable X86_FEATURE_NT_GOOD on AMD Zen Ankur Arora
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