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Re: [Qemu-devel] vga optmization
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] vga optmization |
Date: |
Wed, 05 Nov 2008 14:42:22 +0000 |
User-agent: |
Thunderbird 2.0.0.14 (X11/20080505) |
Glauber Costa wrote:
>> That's also how currently qemu-xen works.
>> I am glad that we agree :)
>
> I'm attaching a new version. Let me know if it's better this way.
>
Yes, this is much better thanks.
I still have comments about possible improvements, so I wrote patch
(against your patch).
This patch is not meant to be applied, is only meant to be read (I believe
that C code is more meaningful than English :).
Some of the changes include:
- instead of adding cirrus_lfb_addr, add a more generic lfb_addr to
VGAState, so that can be reused in the future for possible stdvga only
mappings;
- instead of using cirrus_lfb_mapped as a boolean, use it as the
mapping address, it is more useful that way;
- instead of keeping the kvm dirty map always enabled, enable it only
when the framebuffer is linear and in graphical mode;
- look at the changes to vga.c, there is a simple check to reduce the
dirty area to sync.
It would be nice to check if the last two changes are actually a
performance improvement.
diff -r a5bcebe9e2bc hw/cirrus_vga.c
--- a/hw/cirrus_vga.c Wed Nov 05 12:09:13 2008 +0000
+++ b/hw/cirrus_vga.c Wed Nov 05 14:29:54 2008 +0000
@@ -249,9 +249,6 @@
int cirrus_linear_io_addr;
int cirrus_linear_bitblt_io_addr;
int cirrus_mmio_io_addr;
- uint32_t cirrus_lfb_addr;
- uint32_t cirrus_lfb_end;
- uint32_t cirrus_lfb_mapped;
uint32_t cirrus_addr_mask;
uint32_t linear_mmio_mask;
uint8_t cirrus_shadow_gr0;
@@ -2655,9 +2652,10 @@
static void map_linear_vram(CirrusVGAState *s)
{
- if (!s->cirrus_lfb_mapped && s->cirrus_lfb_addr && s->cirrus_lfb_end) {
- set_vram_mapping(s->cirrus_lfb_addr, s->cirrus_lfb_end,
s->vram_offset);
- s->cirrus_lfb_mapped = 1;
+ if (!s->map_addr && s->lfb_addr && s->lfb_end) {
+ set_vram_mapping(s->lfb_addr, s->lfb_end, s->vram_offset);
+ s->map_addr = s->lfb_addr;
+ s->map_end = s->lfb_end;
}
if(!(s->cirrus_srcptr != s->cirrus_srcptr_end)
@@ -2674,10 +2672,10 @@
static void unmap_linear_vram(CirrusVGAState *s)
{
- if (s->cirrus_lfb_mapped && s->cirrus_lfb_addr && s->cirrus_lfb_end) {
- unset_vram_mapping(s->cirrus_lfb_addr,
- s->cirrus_lfb_end);
- s->cirrus_lfb_mapped = 0;
+ if (s->map_addr && s->lfb_addr && s->lfb_end) {
+ unset_vram_mapping(s->lfb_addr,
+ s->lfb_end);
+ s->map_addr = s->map_end = 0;
}
cpu_register_physical_memory(isa_mem_base + 0x000a0000, 0x20000,
@@ -3331,9 +3329,9 @@
cpu_register_physical_memory(addr + 0x1000000, 0x400000,
s->cirrus_linear_bitblt_io_addr);
- s->cirrus_lfb_mapped = 0;
- s->cirrus_lfb_addr = addr;
- s->cirrus_lfb_end = addr + VGA_RAM_SIZE;
+ s->map_addr = 0;
+ s->lfb_addr = addr;
+ s->lfb_end = addr + VGA_RAM_SIZE;
}
static void cirrus_pci_mmio_map(PCIDevice *d, int region_num,
diff -r a5bcebe9e2bc hw/vga.c
--- a/hw/vga.c Wed Nov 05 12:09:13 2008 +0000
+++ b/hw/vga.c Wed Nov 05 14:29:54 2008 +0000
@@ -1244,6 +1244,9 @@
vga_draw_glyph8_func *vga_draw_glyph8;
vga_draw_glyph9_func *vga_draw_glyph9;
+ /* disable dirty bit tracking */
+ // kvm_log_stop();
+
full_update |= update_palette16(s);
palette = s->last_palette;
@@ -1569,7 +1572,8 @@
uint32_t v, addr1, addr;
vga_draw_line_func *vga_draw_line;
- qemu_physical_sync_dirty_bitmap(s->vram_offset, s->vram_offset +
VGA_RAM_SIZE);
+ /* Enable dirty bit tracking */
+ // kvm_log_start
full_update |= update_basic_params(s);
@@ -1657,6 +1661,31 @@
s->cursor_invalidate(s);
line_offset = s->line_offset;
+
+ if (s->lfb_addr) {
+ if (height - 1 > s->line_compare || multi_run || (s->cr[0x17] & 3) !=
3) {
+ /* Tricky things happen, just track all video memory */
+ start = 0;
+ end = s->vram_size;
+ } else {
+ /* Tricky things won't have any effect, i.e. we are in the very
simple
+ * (and very usual) case of a linear buffer. */
+ /* use page table dirty bit tracking for the LFB plus border */
+ start = (s->start_addr * 4) & TARGET_PAGE_MASK;
+ end = ((s->start_addr * 4 + height * line_offset) +
TARGET_PAGE_SIZE - 1) & TARGET_PAGE_MASK;
+ }
+
+ for (y = 0 ; y < start; y += TARGET_PAGE_SIZE)
+ /* We will not read that anyway. */
+ cpu_physical_memory_set_dirty(s->vram_offset + y);
+
+ qemu_physical_sync_dirty_bitmap(s->lfb_addr + y, end);
+
+ for ( ; y < s->vram_size; y += TARGET_PAGE_SIZE)
+ /* We will not read that anyway. */
+ cpu_physical_memory_set_dirty(s->vram_offset + y);
+ }
+
#if 0
printf("w=%d h=%d v=%d line_offset=%d cr[0x09]=0x%02x cr[0x17]=0x%02x
linecmp=%d sr[0x01]=0x%02x\n",
width, height, v, line_offset, s->cr[9], s->cr[0x17],
s->line_compare, s->sr[0x01]);
@@ -1746,6 +1775,10 @@
return;
if (s->last_scr_width <= 0 || s->last_scr_height <= 0)
return;
+
+ /* disable dirty bit tracking */
+ // kvm_log_stop();
+
if (s->ds->depth == 8)
val = s->rgb_to_pixel(0, 0, 0);
else
diff -r a5bcebe9e2bc hw/vga_int.h
--- a/hw/vga_int.h Wed Nov 05 12:09:13 2008 +0000
+++ b/hw/vga_int.h Wed Nov 05 14:29:54 2008 +0000
@@ -106,6 +106,10 @@
unsigned int bios_size; \
target_phys_addr_t base_ctrl; \
int it_shift; \
+ unsigned long lfb_addr; \
+ unsigned long lfb_end; \
+ uint32_t map_addr; \
+ uint32_t map_end; \
PCIDevice *pci_dev; \
uint32_t latch; \
uint8_t sr_index; \
- Re: [Qemu-devel] vga optmization, (continued)
- Re: [Qemu-devel] vga optmization, Glauber Costa, 2008/11/04
- Re: [Qemu-devel] vga optmization, Avi Kivity, 2008/11/04
- Re: [Qemu-devel] vga optmization, Anthony Liguori, 2008/11/04
- Re: [Qemu-devel] vga optmization, Glauber Costa, 2008/11/04
- Re: [Qemu-devel] vga optmization, Stefano Stabellini, 2008/11/04
- Re: [Qemu-devel] vga optmization, Avi Kivity, 2008/11/04
- Re: [Qemu-devel] vga optmization, Anthony Liguori, 2008/11/04
- Re: [Qemu-devel] vga optmization, Stefano Stabellini, 2008/11/04
- Re: [Qemu-devel] vga optmization, Glauber Costa, 2008/11/04
- Re: [Qemu-devel] vga optmization, Anthony Liguori, 2008/11/04
- Re: [Qemu-devel] vga optmization,
Stefano Stabellini <=
- Re: [Qemu-devel] vga optmization, Glauber Costa, 2008/11/07
- Re: [Qemu-devel] vga optmization, Stefano Stabellini, 2008/11/07