r300g: rework command submission and resource space checking

The motivation behind this rework is to get some speed by reducing
CPU overhead. The performance increase depends on many factors,
but it's measurable (I think it's about 10% increase in Torcs).

This commit replaces libdrm's radeon_cs_gem with our own implemention.
It's optimized specifically for r300g, but r600g could use it as well.
Reloc writes and space checking are faster and simpler than their
counterparts in libdrm (the time complexity of all the functions
is O(1) in nearly all scenarios, thanks to hashing).
(libdrm's radeon_bo_gem is still being used in the driver.)

It works like this:

cs_add_reloc(cs, buf, read_domain, write_domain) adds a new relocation and
also adds the size of 'buf' to the used_gart and used_vram winsys variables
based on the domains, which are simply or'd for the accounting purposes.
The adding is skipped if the reloc is already present in the list, but it
accounts any newly-referenced domains.

cs_validate is then called, which just checks:
    used_vram/gart < vram/gart_size * 0.8
The 0.8 number allows for some memory fragmentation. If the validation
fails, the pipe driver flushes CS and tries do the validation again,
i.e. it validates only that one operation. If it fails again, it drops
the operation on the floor and prints some nasty message to stderr.

cs_write_reloc(cs, buf) just writes a reloc that has been added using
cs_add_reloc. The read_domain and write_domain parameters have been removed,
because we already specify them in cs_add_reloc.

The space checking has been tested by putting small values in vram/gart_size
variables.

1 files changed, 15 insertions, 26 deletions

diff --git a/src/gallium/drivers/r300/r300_winsys.h b/src/gallium/drivers/r300/r300_winsys.h
index b8324afe51..460da77a4f 100644
--- a/src/gallium/drivers/r300/r300_winsys.h
+++ b/src/gallium/drivers/r300/r300_winsys.h
@@ -42,8 +42,8 @@ struct r300_winsys_buffer;      /* for map/unmap etc. */
 struct r300_winsys_cs_buffer;   /* for write_reloc etc. */
 
 struct r300_winsys_cs {
-    unsigned cdw;       /* Number of used dwords. */
-    uint32_t *buf;      /* The command buffer. */
+    unsigned cdw;                           /* Number of used dwords. */
+    uint32_t buf[R300_MAX_CMDBUF_DWORDS];   /* The command buffer. */
 };
 
 enum r300_value_id {
@@ -239,23 +239,22 @@ struct r300_winsys_screen {
     void (*cs_destroy)(struct r300_winsys_cs *cs);
 
     /**
-     * Add a buffer object to the list of buffers to validate.
+     * Add a new buffer relocation. Every relocation must first be added
+     * before it can be written.
      *
-     * \param cs        A command stream to add buffer for validation against.
-     * \param buf       A winsys buffer to validate.
-     * \param rd        A read domain containing a bitmask
-     *                  of the R300_DOMAIN_* flags.
-     * \param wd        A write domain containing a bitmask
-     *                  of the R300_DOMAIN_* flags.
+     * \param cs  A command stream to add buffer for validation against.
+     * \param buf A winsys buffer to validate.
+     * \param rd  A read domain containing a bitmask of the R300_DOMAIN_* flags.
+     * \param wd  A write domain containing a bitmask of the R300_DOMAIN_* flags.
      */
-    void (*cs_add_buffer)(struct r300_winsys_cs *cs,
-                          struct r300_winsys_cs_buffer *buf,
-                          enum r300_buffer_domain rd,
-                          enum r300_buffer_domain wd);
+    void (*cs_add_reloc)(struct r300_winsys_cs *cs,
+                         struct r300_winsys_cs_buffer *buf,
+                         enum r300_buffer_domain rd,
+                         enum r300_buffer_domain wd);
 
     /**
-     * Revalidate all currently set up winsys buffers.
-     * Returns TRUE if a flush is required.
+     * Return TRUE if there is enough memory in VRAM and GTT for the relocs
+     * added so far.
      *
      * \param cs        A command stream to validate.
      */
@@ -270,9 +269,7 @@ struct r300_winsys_screen {
      * \param wd        A write domain containing a bitmask of the R300_DOMAIN_* flags.
      */
     void (*cs_write_reloc)(struct r300_winsys_cs *cs,
-                           struct r300_winsys_cs_buffer *buf,
-                           enum r300_buffer_domain rd,
-                           enum r300_buffer_domain wd);
+                           struct r300_winsys_cs_buffer *buf);
 
     /**
      * Flush a command stream.
@@ -294,14 +291,6 @@ struct r300_winsys_screen {
                          void *user);
 
     /**
-     * Reset the list of buffer objects to validate, usually called
-     * prior to adding buffer objects for validation.
-     *
-     * \param cs        A command stream to reset buffers for.
-     */
-    void (*cs_reset_buffers)(struct r300_winsys_cs *cs);
-
-    /**
      * Return TRUE if a buffer is referenced by a command stream or by hardware
      * (i.e. is busy), based on the domain parameter.
      *