From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Michal Hocko <mhocko@kernel.org>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Sistare <steven.sistare@oracle.com>
Subject: Re: [PATCH v2] x86/mm: use max memory block size on bare metal
Date: Thu, 11 Jun 2020 12:59:10 -0400 [thread overview]
Message-ID: <20200611165910.6dwd3c7z5brimjbm@ca-dmjordan1.us.oracle.com> (raw)
In-Reply-To: <dc869b25-db3c-8c68-3278-8688c5288632@intel.com>
On Thu, Jun 11, 2020 at 07:16:02AM -0700, Dave Hansen wrote:
> On 6/9/20 3:54 PM, Daniel Jordan wrote:
> > + /*
> > + * Use max block size to minimize overhead on bare metal, where
> > + * alignment for memory hotplug isn't a concern.
> > + */
> > + if (hypervisor_is_type(X86_HYPER_NATIVE)) {
> > + bz = MAX_BLOCK_SIZE;
> > + goto done;
> > + }
>
> What ends up being the worst case scenario? Booting a really small
> bare-metal x86 system, say with 64MB or 128MB of RAM? What's the
> overhead there?
Might not be following you, so bear with me, but we only get to this check on a
system with a physical address end of at least MEM_SIZE_FOR_LARGE_BLOCK (64G),
and this would still (ever so slightly...) reduce overhead of memory block init
at boot in that case.
next prev parent reply other threads:[~2020-06-11 16:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-09 22:54 Daniel Jordan
2020-06-09 23:03 ` Daniel Jordan
2020-06-10 7:20 ` David Hildenbrand
2020-06-10 7:30 ` David Hildenbrand
2020-06-10 17:16 ` Daniel Jordan
2020-06-11 14:16 ` Dave Hansen
2020-06-11 16:59 ` Daniel Jordan [this message]
2020-06-11 17:05 ` Dave Hansen
2020-06-12 3:29 ` Daniel Jordan
2020-06-19 12:07 ` Michal Hocko
2020-06-22 19:17 ` Daniel Jordan
2020-06-26 12:47 ` Michal Hocko
2020-07-08 18:46 ` Daniel Jordan
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