d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use an alignment of 1 instead of PAGE_SIZE for the rx and tx buffer tags.

Browse Source 
Since the e1000 DMA engines hava no constraints on the alignment of buffer
transfers, there is no reason to tell busdma that there is.  This save a
minimum of 1 malloc call per packet, which translates to eliminating 4 locks.
It also means that buffers are not needlessly bounced when transfered.  The
end result is a 38% improvement in pps in a 4 way bridging environment.

Obtained from: Sandvine, Inc.
This commit is contained in:
Scott Long 2004-10-19 02:39:27 +00:00
parent e30c35ed0c
commit 25ba7fd287
1 changed files with 2 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
sys/dev/em/if_em.c
View File

@ -2056,13 +2056,6 @@ em_dma_malloc(struct adapter *adapter, bus_size_t size,
goto fail_0;
}
r = bus_dmamap_create(dma->dma_tag, BUS_DMA_NOWAIT, &dma->dma_map);
if (r != 0) {
printf("em%d: em_dma_malloc: bus_dmamap_create failed; "
"error %u\n", adapter->unit, r);
goto fail_1;
}
r = bus_dmamem_alloc(dma->dma_tag, (void**) &dma->dma_vaddr,
BUS_DMA_NOWAIT, &dma->dma_map);
if (r != 0) {
@ -2090,8 +2083,6 @@ em_dma_malloc(struct adapter *adapter, bus_size_t size,
bus_dmamap_unload(dma->dma_tag, dma->dma_map);
fail_2:
bus_dmamem_free(dma->dma_tag, dma->dma_vaddr, dma->dma_map);
fail_1:
bus_dmamap_destroy(dma->dma_tag, dma->dma_map);
bus_dma_tag_destroy(dma->dma_tag);
fail_0:
dma->dma_map = NULL;
@ -2104,7 +2095,6 @@ em_dma_free(struct adapter *adapter, struct em_dma_alloc *dma)
{
bus_dmamap_unload(dma->dma_tag, dma->dma_map);
bus_dmamem_free(dma->dma_tag, dma->dma_vaddr, dma->dma_map);
bus_dmamap_destroy(dma->dma_tag, dma->dma_map);
bus_dma_tag_destroy(dma->dma_tag);
}
@ -2145,7 +2135,7 @@ em_setup_transmit_structures(struct adapter * adapter)
* Setup DMA descriptor areas.
*/
if (bus_dma_tag_create(NULL, /* parent */
PAGE_SIZE, 0, /* alignment, bounds */
1, 0, /* alignment, bounds */
BUS_SPACE_MAXADDR, /* lowaddr */
BUS_SPACE_MAXADDR, /* highaddr */
NULL, NULL, /* filter, filterarg */
@ -2523,7 +2513,7 @@ em_allocate_receive_structures(struct adapter * adapter)
sizeof(struct em_buffer) * adapter->num_rx_desc);
error = bus_dma_tag_create(NULL, /* parent */
PAGE_SIZE, 0, /* alignment, bounds */
1, 0, /* alignment, bounds */
BUS_SPACE_MAXADDR, /* lowaddr */
BUS_SPACE_MAXADDR, /* highaddr */
NULL, NULL, /* filter, filterarg */