From: Oscar Salvador <osalvador@suse.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/3] x86/vmemmap: Drop handling of 1GB vmemmap ranges
Date: Mon, 8 Mar 2021 19:48:40 +0100 [thread overview]
Message-ID: <20210308184840.GC25767@linux> (raw)
In-Reply-To: <62c5b490-353a-ca3a-d2c8-f02189210c32@intel.com>
On Thu, Mar 04, 2021 at 10:42:59AM -0800, Dave Hansen wrote:
> On 3/1/21 12:32 AM, Oscar Salvador wrote:
> > We never get to allocate 1GB pages when mapping the vmemmap range.
> > Drop the dead code both for the aligned and unaligned cases and leave
> > only the direct map handling.
>
> Could you elaborate a bit on why 1GB pages are never used? It is just
> unlikely to have a 64GB contiguous area of memory that needs 1GB of
> contiguous vmemmap? Or, does the fact that sections are smaller than
> 64GB keeps this from happening?
AFAIK, the biggest we populate vmemmap pages with is 2MB, plus the fact
that as you pointed out, memory sections on x86_64 are 128M, which is
way smaller than what would require to allocate a 1GB for vmemmap pages.
Am I missing something?
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-03-08 18:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 8:32 [PATCH v4 0/3] Cleanup and fixups for vmemmap handling Oscar Salvador
2021-03-01 8:32 ` [PATCH v4 1/3] x86/vmemmap: Drop handling of 4K unaligned vmemmap range Oscar Salvador
2021-03-04 15:50 ` Dave Hansen
2021-03-08 18:20 ` Oscar Salvador
2021-03-08 18:26 ` Dave Hansen
2021-03-01 8:32 ` [PATCH v4 2/3] x86/vmemmap: Drop handling of 1GB vmemmap ranges Oscar Salvador
2021-03-04 18:42 ` Dave Hansen
2021-03-08 18:48 ` Oscar Salvador [this message]
2021-03-08 19:25 ` David Hildenbrand
2021-03-01 8:32 ` [PATCH v4 3/3] x86/vmemmap: Handle unpopulated sub-pmd ranges Oscar Salvador
2021-03-04 17:02 ` Dave Hansen
2021-03-04 17:08 ` Dave Hansen
2021-03-05 18:26 ` David Hildenbrand
2021-03-08 18:43 ` Oscar Salvador
2021-03-09 8:25 ` Oscar Salvador
2021-03-09 14:50 ` Dave Hansen
2021-03-09 19:39 ` Zi Yan
2021-03-09 21:26 ` Oscar Salvador
2021-03-03 0:09 ` [PATCH v4 0/3] Cleanup and fixups for vmemmap handling Andrew Morton
2021-03-03 18:38 ` Borislav Petkov
2021-03-03 23:04 ` Andrew Morton
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