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From: vans163 <vans_163@yahoo.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [Bug 1618122] [NEW] qemu-monitor screendump very slow
Date: Mon, 29 Aug 2016 16:00:30 -0000	[thread overview]
Message-ID: <20160829160030.27613.81837.malonedeb@gac.canonical.com> (raw)

Public bug reported:

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
--------------------------------------------------------------------------------
56,592,286,124  PROGRAM TOTALS

--------------------------------------------------------------------------------
            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]

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.

** Affects: qemu
     Importance: Undecided
         Status: New

** 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
  
  --------------------------------------------------------------------------------
-             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]
+  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]
  
- I tried taking a look on how to fix this, but it seems pixmap is deeply
+ 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 starts.
  
  For example this is DisplaySurface:
  
  struct DisplaySurface {
-     pixman_format_code_t format;
-     pixman_image_t *image;
-     uint8_t flags;
+     pixman_format_code_t format;
+     pixman_image_t *image;
+     uint8_t flags;
  #ifdef CONFIG_OPENGL
-     GLenum glformat;
-     GLenum gltype;
-     GLuint texture;
+     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.

** 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
  --------------------------------------------------------------------------------
  56,592,286,124  PROGRAM TOTALS
  
  --------------------------------------------------------------------------------
              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]
  
  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 starts.
+ 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.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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
  --------------------------------------------------------------------------------
  56,592,286,124  PROGRAM TOTALS

  --------------------------------------------------------------------------------
              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]

  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.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1618122/+subscriptions

             reply	other threads:[~2016-08-29 16:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-29 16:00 vans163 [this message]
2016-08-29 17:39 ` [Qemu-devel] [Bug 1618122] Re: qemu-monitor screendump very slow vans163
2016-08-29 18:55 ` vans163
2016-08-29 19:01 ` vans163
2016-08-31 12:53 ` vans163
2021-04-22  5:21 ` Thomas Huth
2021-06-22  4:17 ` Launchpad Bug Tracker

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