[PATCH 0/2] xen/mm: Optimize init_heap_pages()

From: Julien Grall <julien@xen.org>
To: xen-devel@lists.xenproject.org
Cc: bertrand.marquis@arm.com, Julien Grall <jgrall@amazon.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Jan Beulich <jbeulich@suse.com>, Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>
Subject: [PATCH 0/2] xen/mm: Optimize init_heap_pages()
Date: Thu,  9 Jun 2022 09:30:37 +0100	[thread overview]
Message-ID: <20220609083039.76667-1-julien@xen.org> (raw)

From: Julien Grall <jgrall@amazon.com>

Hi all,

As part of the Live-Update work, we noticed that a big part Xen boot
is spent to add pages in the heap. For instance, on when running Xen
in a nested envionment on a c5.metal, it takes ~1.5s.

This small series is reworking init_heap_pages() to give the pages
to free_heap_pages() by chunk rather than one by one.

With this approach, the time spent to init the heap is down
to 166 ms in the setup mention above.

There is potentially one more optimization possible that would
allow to further reduce the time spent. The new approach is accessing
the page information multiple time in separate loop that can potentially
be large.

Cheers,

Hongyan Xia (1):
  xen/heap: pass order to free_heap_pages() in heap init

Julien Grall (1):
  xen/heap: Split init_heap_pages() in two

 xen/common/page_alloc.c | 109 ++++++++++++++++++++++++++++++----------
 1 file changed, 82 insertions(+), 27 deletions(-)

-- 
2.32.0