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[Qemu-devel] [Bug 1618122] Re: qemu-monitor screendump very slow
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From: |
vans163 |
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Subject: |
[Qemu-devel] [Bug 1618122] Re: qemu-monitor screendump very slow |
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Date: |
Mon, 29 Aug 2016 18:55:16 -0000 |
** Description changed:
qemu-monitor screendump often using 10-20% cpu usage of one core to take
a small capture.
Most of the CPU usage seems to come from libpixman. There were many
reports of libpixman becoming 8 times slower in newer releases.
https://github.com/qemu/qemu/blob/0c56c6ab68902281094c7aac6305e2321c34c187/ui/console.c#L285
Simple Valgrind Ir report.
--------------------------------------------------------------------------------
- Ir
+ Ir
--------------------------------------------------------------------------------
- 56,592,286,124 PROGRAM TOTALS
+ 9,994,313,959 PROGRAM TOTALS
--------------------------------------------------------------------------------
- Ir file:function
+ Ir file:function
--------------------------------------------------------------------------------
- 40,288,379,712 ???:0x000000000000caa0 [/usr/lib64/libpixman-1.so.0.34.0]
- 3,585,795,168 ???:0x000000000006df20 [/usr/lib64/libpixman-1.so.0.34.0]
- 1,763,982,432 ???:0x0000000000052360 [/usr/lib64/libpixman-1.so.0.34.0]
- 1,517,832,033 ???:__memcpy_sse2_unaligned [/usr/lib64/libc-2.23.so]
- 993,997,885 ???:__GI_mempcpy [/usr/lib64/libc-2.23.so]
- 484,059,456 ???:0x0000000000050430 [/usr/lib64/libpixman-1.so.0.34.0]
- 460,109,168 ???:pixman_image_composite32
[/usr/lib64/libpixman-1.so.0.34.0]
+ 4,883,603,360
/usr/src/debug/pixman-0.34.0/pixman/pixman-access.c:store_scanline_b8g8r8
[/usr/lib64/libpixman-1.so.0.34.0]
+ 282,312,800
/usr/src/debug/pixman-0.34.0/pixman/pixman-implementation.c:_pixman_implementation_iter_init
[/usr/lib64/libpixman-1.so.0.34.0]
+ 267,394,160
/usr/src/debug/pixman-0.34.0/pixman/pixman-sse2.c:sse2_fetch_x8r8g8b8
[/usr/lib64/libpixman-1.so.0.34.0]
+ 256,761,600
/usr/src/debug/pixman-0.34.0/pixman/pixman-private.h:store_scanline_b8g8r8
+ 254,676,199 ???:0x0000000000011f40 [/usr/lib64/libjemalloc.so.2]
+ 199,990,526 ???:0x0000000000011a10 [/usr/lib64/libjemalloc.so.2]
- I tried taking a look on how to fix this, but it seems pixman is deeply
- enrooted inside the monitor. I wanted to try to simply take whats on
- the display and memcpy it into .ppm format manually creating the file
- header, but I cant figure out where the raw display buffer/image is
- gotten from.
+
+ I tried taking a look on how to fix this, but it seems pixman is deeply
enrooted inside the monitor. I wanted to try to simply take whats on the
display and memcpy it into .ppm format manually creating the file header, but I
cant figure out where the raw display buffer/image is gotten from.
For example this is DisplaySurface:
struct DisplaySurface {
pixman_format_code_t format;
pixman_image_t *image;
uint8_t flags;
#ifdef CONFIG_OPENGL
GLenum glformat;
GLenum gltype;
GLuint texture;
#endif
};
Which as you can see already has the pixman_image_t. Maybe I should just
work with that pixman_image_t?
The most effective solution IMO seems to just memcpy from the display
into a premade header for a .ppm or .bmp file assuming 24 or 32 bpp. No
need for libpixman.
--
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https://bugs.launchpad.net/bugs/1618122
Title:
qemu-monitor screendump very slow
Status in QEMU:
New
Bug description:
qemu-monitor screendump often using 10-20% cpu usage of one core to
take a small capture.
Most of the CPU usage seems to come from libpixman. There were many
reports of libpixman becoming 8 times slower in newer releases.
https://github.com/qemu/qemu/blob/0c56c6ab68902281094c7aac6305e2321c34c187/ui/console.c#L285
Simple Valgrind Ir report.
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
9,994,313,959 PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
4,883,603,360
/usr/src/debug/pixman-0.34.0/pixman/pixman-access.c:store_scanline_b8g8r8
[/usr/lib64/libpixman-1.so.0.34.0]
282,312,800
/usr/src/debug/pixman-0.34.0/pixman/pixman-implementation.c:_pixman_implementation_iter_init
[/usr/lib64/libpixman-1.so.0.34.0]
267,394,160
/usr/src/debug/pixman-0.34.0/pixman/pixman-sse2.c:sse2_fetch_x8r8g8b8
[/usr/lib64/libpixman-1.so.0.34.0]
256,761,600
/usr/src/debug/pixman-0.34.0/pixman/pixman-private.h:store_scanline_b8g8r8
254,676,199 ???:0x0000000000011f40 [/usr/lib64/libjemalloc.so.2]
199,990,526 ???:0x0000000000011a10 [/usr/lib64/libjemalloc.so.2]
I tried taking a look on how to fix this, but it seems pixman is deeply
enrooted inside the monitor. I wanted to try to simply take whats on the
display and memcpy it into .ppm format manually creating the file header, but I
cant figure out where the raw display buffer/image is gotten from.
For example this is DisplaySurface:
struct DisplaySurface {
pixman_format_code_t format;
pixman_image_t *image;
uint8_t flags;
#ifdef CONFIG_OPENGL
GLenum glformat;
GLenum gltype;
GLuint texture;
#endif
};
Which as you can see already has the pixman_image_t. Maybe I should
just work with that pixman_image_t?
The most effective solution IMO seems to just memcpy from the display
into a premade header for a .ppm or .bmp file assuming 24 or 32 bpp.
No need for libpixman.
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