From: David Miller <davem@davemloft.net>
To: willy@infradead.org
Cc: pasha.tatashin@oracle.com, linux-kernel@vger.kernel.org,
sparclinux@vger.kernel.org, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.or
Subject: Re: [v1 0/5] parallelized "struct page" zeroing
Date: Thu, 23 Mar 2017 16:35:20 -0700 (PDT) [thread overview]
Message-ID: <20170323.163520.123614131649571916.davem@davemloft.net> (raw)
In-Reply-To: <20170323232638.GB29134@bombadil.infradead.org>
From: Matthew Wilcox <willy@infradead.org>
Date: Thu, 23 Mar 2017 16:26:38 -0700
> On Thu, Mar 23, 2017 at 07:01:48PM -0400, Pavel Tatashin wrote:
>> When deferred struct page initialization feature is enabled, we get a
>> performance gain of initializing vmemmap in parallel after other CPUs are
>> started. However, we still zero the memory for vmemmap using one boot CPU.
>> This patch-set fixes the memset-zeroing limitation by deferring it as well.
>>
>> Here is example performance gain on SPARC with 32T:
>> base
>> https://hastebin.com/ozanelatat.go
>>
>> fix
>> https://hastebin.com/utonawukof.go
>>
>> As you can see without the fix it takes: 97.89s to boot
>> With the fix it takes: 46.91 to boot.
>
> How long does it take if we just don't zero this memory at all? We seem
> to be initialising most of struct page in __init_single_page(), so it
> seems like a lot of additional complexity to conditionally zero the rest
> of struct page.
Alternatively, just zero out the entire vmemmap area when it is setup
in the kernel page tables.
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next prev parent reply other threads:[~2017-03-23 23:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 23:01 Pavel Tatashin
2017-03-23 23:01 ` [v1 1/5] sparc64: simplify vmemmap_populate Pavel Tatashin
2017-03-23 23:01 ` [v1 2/5] mm: defining memblock_virt_alloc_try_nid_raw Pavel Tatashin
2017-03-23 23:01 ` [v1 3/5] mm: add "zero" argument to vmemmap allocators Pavel Tatashin
2017-03-23 23:01 ` [v1 4/5] mm: zero struct pages during initialization Pavel Tatashin
2017-03-23 23:01 ` [v1 5/5] mm: teach platforms not to zero struct pages memory Pavel Tatashin
2017-03-23 23:26 ` [v1 0/5] parallelized "struct page" zeroing Matthew Wilcox
2017-03-23 23:35 ` David Miller [this message]
2017-03-23 23:47 ` Pasha Tatashin
2017-03-24 1:15 ` Pasha Tatashin
2017-03-23 23:36 ` Pasha Tatashin
2017-03-24 8:51 ` Christian Borntraeger
2017-03-24 9:35 ` Heiko Carstens
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