[src/trunk]: src/sys/dev/sdmmc Add small command queue to reduce latency betw...

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2ba728c31728
branches:  trunk
changeset: 339784:2ba728c31728
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Sun Aug 09 13:49:18 2015 +0000

description:
Add small command queue to reduce latency between ld driver and
sdmmc I/O thread.

diffstat:

 sys/dev/sdmmc/ld_sdmmc.c |  16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diffs (58 lines):

diff -r c7493fa44889 -r 2ba728c31728 sys/dev/sdmmc/ld_sdmmc.c
--- a/sys/dev/sdmmc/ld_sdmmc.c  Sun Aug 09 13:46:50 2015 +0000
+++ b/sys/dev/sdmmc/ld_sdmmc.c  Sun Aug 09 13:49:18 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ld_sdmmc.c,v 1.19 2015/08/03 10:09:08 jmcneill Exp $   */
+/*     $NetBSD: ld_sdmmc.c,v 1.20 2015/08/09 13:49:18 mlelstv Exp $    */
 
 /*
  * Copyright (c) 2008 KIYOHARA Takashi
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ld_sdmmc.c,v 1.19 2015/08/03 10:09:08 jmcneill Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ld_sdmmc.c,v 1.20 2015/08/09 13:49:18 mlelstv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_sdmmc.h"
@@ -71,7 +71,9 @@
        int sc_hwunit;
 
        struct sdmmc_function *sc_sf;
-       struct ld_sdmmc_task sc_task;
+#define LD_SDMMC_MAXQUEUECNT 4
+       struct ld_sdmmc_task sc_task[LD_SDMMC_MAXQUEUECNT];
+       int sc_nexttask;
 };
 
 static int ld_sdmmc_match(device_t, cfdata_t, void *);
@@ -115,6 +117,8 @@
            sa->sf->cid.rev, sa->sf->cid.psn, sa->sf->cid.mdt);
        aprint_naive("\n");
 
+       sc->sc_nexttask = 0;
+
        sc->sc_hwunit = 0;      /* always 0? */
        sc->sc_sf = sa->sf;
 
@@ -122,7 +126,7 @@
        ld->sc_secperunit = sc->sc_sf->csd.capacity;
        ld->sc_secsize = SDMMC_SECTOR_SIZE;
        ld->sc_maxxfer = MAXPHYS;
-       ld->sc_maxqueuecnt = 1;
+       ld->sc_maxqueuecnt = LD_SDMMC_MAXQUEUECNT;
        ld->sc_dump = ld_sdmmc_dump;
        ld->sc_start = ld_sdmmc_start;
 
@@ -175,7 +179,9 @@
 ld_sdmmc_start(struct ld_softc *ld, struct buf *bp)
 {
        struct ld_sdmmc_softc *sc = device_private(ld->sc_dv);
-       struct ld_sdmmc_task *task = &sc->sc_task;
+       struct ld_sdmmc_task *task = &sc->sc_task[sc->sc_nexttask];
+
+       sc->sc_nexttask = (sc->sc_nexttask + 1) % LD_SDMMC_MAXQUEUECNT;
 
        task->task_sc = sc;
        task->task_bp = bp;