> On 11/06/2017 08:30 PM, aravindan.muthuku...@intel.com wrote:
> > From: Aravindan Muthukumar <aravindan.muthuku...@intel.com>
> >
> > Now the complexity has been reduced to O(1)
> >
> > Algorithm calculates the index using matrix method.
> > Matrix arrangement is as below:
> > Assuming PAGE_SIZE is 4096.
> >
> > 1*4096 2*4096 3*4096 4*4096
> > 5*4096 6*4096 7*4096 8*4096
> > 10*4096 12*4096 14*4096 16*4096
> > 20*4096 24*4096 28*4096 32*4096
> > ... ... ... ...
> > ... ... ... ...
> > ... ... ... max_cache_size
> >
> > From this matrix its clearly seen that every row follows the below
> > way:
> > ... ... ... n
> > n+(1/4)n n+(1/2)n n+(3/4)n 2n
> >
> > Row is calculated as log2(size/PAGE_SIZE) Column is calculated as
> > converting the difference between the elements to fit into power size
> > of two and indexing it.
> >
> > Final Index is (row*4)+(col-1)
> >
> > Tested with Intel Mesa CI.
> >
> > Improves performance of 3DMark on BXT by 0.705966% +/- 0.229767%
> > (n=20)
> >
> > v3: review comments implemented (Ian).
> > v2: review comments implemented (Jason).
> >
> > Signed-off-by: Aravindan Muthukumar <aravindan.muthuku...@intel.com>
> > Signed-off-by: Kedar Karanje <kedar.j.kara...@intel.com>
> > Reviewed-by: Yogesh Marathe <yogesh.mara...@intel.com>
> > ---
> > src/mesa/drivers/dri/i965/brw_bufmgr.c | 38
> > +++++++++++++++++++++++++++-------
> > 1 file changed, 30 insertions(+), 8 deletions(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> > b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> > index 17036b5..9a423da 100644
> > --- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> > +++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> > @@ -86,6 +86,8 @@
> >
> > #define memclear(s) memset(&s, 0, sizeof(s))
> >
> > +#define PAGE_SIZE 4096
> > +
> > #define FILE_DEBUG_FLAG DEBUG_BUFMGR
> >
> > static inline int
> > @@ -180,19 +182,35 @@ bo_tile_pitch(struct brw_bufmgr *bufmgr, uint32_t
> pitch, uint32_t tiling)
> > return ALIGN(pitch, tile_width);
> > }
> >
> > +/*
> > + * This function finds the correct bucket fit for the input size.
> > + * The function works with O(1) complexity when the requested size
> > + * was queried instead of iterating the size through all the buckets.
> > + */
> > static struct bo_cache_bucket *
> > bucket_for_size(struct brw_bufmgr *bufmgr, uint64_t size) {
> > - int i;
> > + /* Calculating the pages and rounding up to the page size. */
> > + const unsigned int pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
> >
> > - for (i = 0; i < bufmgr->num_buckets; i++) {
> > - struct bo_cache_bucket *bucket = &bufmgr->cache_bucket[i];
> > - if (bucket->size >= size) {
> > - return bucket;
> > - }
> > - }
> > + /* Finding the row number based on the calculated pages. */
> > + const unsigned int rows = 30 - __builtin_clz((pages - 1) | 3);
> >
> > - return NULL;
>
> Why did you make random (and incorrect) style changes and delete
> (useful) comments from the code I sent?
>
> > > Thanks Ian. I added comments based on my understanding and I get the
> > > point I'll push v4 with your comments.
> > + const unsigned int row_max_pages = 4 << rows;
> > + const unsigned int prev_row_max_pages = (row_max_pages / 2) & ~2;
> > +
> > + /* Finding the column number using column interval. */
> > + int col_size_log2 = rows - 1;
> > + col_size_log2 += (col_size_log2 < 0);
> > +
> > + const unsigned int col = ( (pages - prev_row_max_pages +
> > + ( (1 << col_size_log2) - 1) ) >>
> > + col_size_log2 );
> > +
> > + /* Calculating the index based on the row and column. */
> > + const unsigned int index = (rows * 4) + (col - 1);
> > +
> > + return (index < bufmgr->num_buckets) ?
> > + &bufmgr->cache_bucket[index] : NULL;
> > }
> >
> > int
> > @@ -1254,6 +1272,10 @@ add_bucket(struct brw_bufmgr *bufmgr, int size)
> > list_inithead(&bufmgr->cache_bucket[i].head);
> > bufmgr->cache_bucket[i].size = size;
> > bufmgr->num_buckets++;
> > +
> > + assert(bucket_for_size(bufmgr, size) == &bufmgr->cache_bucket[i]);
> > + assert(bucket_for_size(bufmgr, size - 2048) ==
> > &bufmgr->cache_bucket[i]);
> > + assert(bucket_for_size(bufmgr, size + 1) !=
> > + &bufmgr->cache_bucket[i]);
> > }
> >
> > static void
> >
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
