[Xen-changelog] [xen-unstable] [LINUX] Improve single-page contiguous region creation/destruction

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID 33aca302b6109179194276885d7b29e0ad5033ab
# Parent  10fb002727ef3df7c06d920af565efd8f3acfdc7
[LINUX] Improve single-page contiguous region creation/destruction

Batch page table updates and fold TLB flush into last one, reducing
number of hypercalls made from ((# of pages) + 1) to just 1.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c |   41 ++++++++++++++-----------
 1 files changed, 23 insertions(+), 18 deletions(-)

diff -r 10fb002727ef -r 33aca302b610 
linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c
--- a/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c    Tue Jul 25 15:50:04 
2006 +0100
+++ b/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c    Tue Jul 25 15:58:35 
2006 +0100
@@ -266,6 +266,7 @@ static void contiguous_bitmap_clear(
 /* Protected by balloon_lock. */
 #define MAX_CONTIG_ORDER 9 /* 2MB */
 static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
+static multicall_entry_t cr_mcl[1<<MAX_CONTIG_ORDER];
 
 /* Ensure multi-page extents are contiguous in machine memory. */
 int xen_create_contiguous_region(
@@ -310,12 +311,13 @@ int xen_create_contiguous_region(
        /* 1. Zap current PTEs, remembering MFNs. */
        for (i = 0; i < (1UL<<order); i++) {
                in_frames[i] = pfn_to_mfn((__pa(vstart) >> PAGE_SHIFT) + i);
-               if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
-                                                __pte_ma(0), 0))
-                       BUG();
+               MULTI_update_va_mapping(cr_mcl + i, vstart + (i*PAGE_SIZE),
+                                       __pte_ma(0), 0);
                set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i,
                        INVALID_P2M_ENTRY);
        }
+       if (HYPERVISOR_multicall(cr_mcl, i))
+               BUG();
 
        /* 2. Get a new contiguous memory extent. */
        out_frame = __pa(vstart) >> PAGE_SHIFT;
@@ -343,15 +345,16 @@ int xen_create_contiguous_region(
        /* 3. Map the new extent in place of old pages. */
        for (i = 0; i < (1UL<<order); i++) {
                frame = success ? (out_frame + i) : in_frames[i];
-               if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
-                                                pfn_pte_ma(frame,
-                                                           PAGE_KERNEL),
-                                                0))
-                       BUG();
+               MULTI_update_va_mapping(cr_mcl + i, vstart + (i*PAGE_SIZE),
+                                       pfn_pte_ma(frame, PAGE_KERNEL), 0);
                set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame);
        }
 
-       flush_tlb_all();
+       cr_mcl[i - 1].args[MULTI_UVMFLAGS_INDEX] = order
+                                                  ? UVMF_TLB_FLUSH|UVMF_ALL
+                                                  : UVMF_INVLPG|UVMF_ALL;
+       if (HYPERVISOR_multicall(cr_mcl, i))
+               BUG();
 
        if (success)
                contiguous_bitmap_set(__pa(vstart) >> PAGE_SHIFT,
@@ -402,13 +405,14 @@ void xen_destroy_contiguous_region(unsig
 
        /* 2. Zap current PTEs. */
        for (i = 0; i < (1UL<<order); i++) {
-               if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
-                                                __pte_ma(0), 0))
-                       BUG();
+               MULTI_update_va_mapping(cr_mcl + i, vstart + (i*PAGE_SIZE),
+                                       __pte_ma(0), 0);
                set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i,
                        INVALID_P2M_ENTRY);
                out_frames[i] = (__pa(vstart) >> PAGE_SHIFT) + i;
        }
+       if (HYPERVISOR_multicall(cr_mcl, i))
+               BUG();
 
        /* 3. Do the exchange for non-contiguous MFNs. */
        rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
@@ -429,15 +433,16 @@ void xen_destroy_contiguous_region(unsig
        /* 4. Map new pages in place of old pages. */
        for (i = 0; i < (1UL<<order); i++) {
                frame = success ? out_frames[i] : (in_frame + i);
-               if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
-                                                pfn_pte_ma(frame,
-                                                           PAGE_KERNEL),
-                                                0))
-                       BUG();
+               MULTI_update_va_mapping(cr_mcl + i, vstart + (i*PAGE_SIZE),
+                                       pfn_pte_ma(frame, PAGE_KERNEL), 0);
                set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame);
        }
 
-       flush_tlb_all();
+       cr_mcl[i - 1].args[MULTI_UVMFLAGS_INDEX] = order
+                                                  ? UVMF_TLB_FLUSH|UVMF_ALL
+                                                  : UVMF_INVLPG|UVMF_ALL;
+       if (HYPERVISOR_multicall(cr_mcl, i))
+               BUG();
 
        balloon_unlock(flags);
 }

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog