Tim,
Thanks for the comments. I will fix them according to your comments, along with
making save/restore work.
Best,
-Wei
-----Original Message-----
From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx]
Sent: Tuesday, February 23, 2010 3:39 AM
To: Huang2, Wei
Cc: 'xen-devel@xxxxxxxxxxxxxxxxxxx'; Keir Fraser; Xu, Dongxiao
Subject: Re: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host page
At 17:18 +0000 on 22 Feb (1266859100), Wei Huang wrote:
> Change page allocation code in Xen tools. The allocation request now
> starts with 1GB; if that fails, then falls back to 2MB and then 4KB.
>
> Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
> Acked-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
>
Content-Description: 2-xen-hap-fix-tools.patch
> # HG changeset patch
> # User huangwei@xxxxxxxxxxxxxxxx
> # Date 1266853449 21600
> # Node ID c9b45664b423e11003358944bb8e6e976e735301
> # Parent 1d166c5703256ab97225c6ae46ac87dd5bd07e89
> fix the tools to support 1GB. Create 1GB pages if possible; otherwise falls
> back to 2MB then 4KB.
>
> diff -r 1d166c570325 -r c9b45664b423 tools/libxc/xc_hvm_build.c
> --- a/tools/libxc/xc_hvm_build.c Mon Feb 22 09:44:04 2010 -0600
> +++ b/tools/libxc/xc_hvm_build.c Mon Feb 22 09:44:09 2010 -0600
> @@ -19,8 +19,10 @@
>
> #include <xen/libelf/libelf.h>
>
> -#define SUPERPAGE_PFN_SHIFT 9
> -#define SUPERPAGE_NR_PFNS (1UL << SUPERPAGE_PFN_SHIFT)
> +#define SUPERPAGE_2MB_SHIFT 9
> +#define SUPERPAGE_2MB_NR_PFNS (1UL << SUPERPAGE_2MB_SHIFT)
> +#define SUPERPAGE_1GB_SHIFT 18
> +#define SUPERPAGE_1GB_NR_PFNS (1UL << SUPERPAGE_1GB_SHIFT)
>
> #define SPECIALPAGE_BUFIOREQ 0
> #define SPECIALPAGE_XENSTORE 1
> @@ -117,6 +119,8 @@
> uint64_t v_start, v_end;
> int rc;
> xen_capabilities_info_t caps;
> + unsigned long stat_normal_pages = 0, stat_2mb_pages = 0,
> + stat_1gb_pages = 0;
> int pod_mode = 0;
>
>
> @@ -166,35 +170,43 @@
>
> /*
> * Allocate memory for HVM guest, skipping VGA hole 0xA0000-0xC0000.
> - * We allocate pages in batches of no more than 8MB to ensure that
> - * we can be preempted and hence dom0 remains responsive.
> + *
> + * We attempt to allocate 1GB pages if possible. It falls back on 2MB
> + * pages if 1GB allocation fails. 4KB pages will be used eventually if
> + * both fail.
> + *
> + * Under 2MB mode, we allocate pages in batches of no more than 8MB to
> + * ensure that we can be preempted and hence dom0 remains responsive.
> */
> rc = xc_domain_memory_populate_physmap(
> xc_handle, dom, 0xa0, 0, 0, &page_array[0x00]);
> cur_pages = 0xc0;
> + stat_normal_pages = 0xc0;
> while ( (rc == 0) && (nr_pages > cur_pages) )
> {
> /* Clip count to maximum 8MB extent. */
ITYM 1GB here.
> unsigned long count = nr_pages - cur_pages;
> - if ( count > 2048 )
> - count = 2048;
> + unsigned long max_pages = SUPERPAGE_1GB_NR_PFNS;
>
> - /* Clip partial superpage extents to superpage boundaries. */
> - if ( ((cur_pages & (SUPERPAGE_NR_PFNS-1)) != 0) &&
> - (count > (-cur_pages & (SUPERPAGE_NR_PFNS-1))) )
> - count = -cur_pages & (SUPERPAGE_NR_PFNS-1); /* clip s.p. tail */
> - else if ( ((count & (SUPERPAGE_NR_PFNS-1)) != 0) &&
> - (count > SUPERPAGE_NR_PFNS) )
> - count &= ~(SUPERPAGE_NR_PFNS - 1); /* clip non-s.p. tail */
> + if ( count > max_pages )
> + count = max_pages;
> +
> + /* Take care the corner cases of super page tails */
> + if ( ((cur_pages & (SUPERPAGE_1GB_NR_PFNS-1)) != 0) &&
> + (count > (-cur_pages & (SUPERPAGE_1GB_NR_PFNS-1))) )
> + count = -cur_pages & (SUPERPAGE_1GB_NR_PFNS-1);
> + else if ( ((count & (SUPERPAGE_1GB_NR_PFNS-1)) != 0) &&
> + (count > SUPERPAGE_1GB_NR_PFNS) )
> + count &= ~(SUPERPAGE_1GB_NR_PFNS - 1);
This logic is overkill since you allocate at most one 1GB page in each
pass. In fact, given that you test for <1GB immediately below, I think
you can just drop this 'tails' chunk entirely.
>
> - /* Attempt to allocate superpage extents. */
> - if ( ((count | cur_pages) & (SUPERPAGE_NR_PFNS - 1)) == 0 )
> + /* Attemp to allocate 1GB super page */
> + if ( ((count | cur_pages) & (SUPERPAGE_1GB_NR_PFNS - 1)) == 0 )
> {
> long done;
> - xen_pfn_t sp_extents[count >> SUPERPAGE_PFN_SHIFT];
> + xen_pfn_t sp_extents[count >> SUPERPAGE_1GB_SHIFT];
> struct xen_memory_reservation sp_req = {
> - .nr_extents = count >> SUPERPAGE_PFN_SHIFT,
> - .extent_order = SUPERPAGE_PFN_SHIFT,
> + .nr_extents = count >> SUPERPAGE_1GB_SHIFT,
> + .extent_order = SUPERPAGE_1GB_SHIFT,
> .domid = dom
> };
>
> @@ -203,11 +215,12 @@
>
> set_xen_guest_handle(sp_req.extent_start, sp_extents);
> for ( i = 0; i < sp_req.nr_extents; i++ )
> - sp_extents[i] =
> page_array[cur_pages+(i<<SUPERPAGE_PFN_SHIFT)];
> + sp_extents[i] =
> page_array[cur_pages+(i<<SUPERPAGE_1GB_SHIFT)];
> done = xc_memory_op(xc_handle, XENMEM_populate_physmap, &sp_req);
> if ( done > 0 )
> {
> - done <<= SUPERPAGE_PFN_SHIFT;
> + stat_1gb_pages += done;
> + done <<= SUPERPAGE_1GB_SHIFT;
> if ( pod_mode && target_pages > cur_pages )
> {
> int d = target_pages - cur_pages;
> @@ -218,12 +231,60 @@
> }
> }
>
> + if ( count != 0 )
> + {
> + max_pages = 2048;
Call this (SUPERPAGE_2MB_NR_PFNS * 4)?
Cheers,
Tim.
--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
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