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SubjectPrezeroing V2 [4/4]: Hardware Zeroing through SGI BTE
o Zeroing driver implemented with the Block Transfer Engine in the Altix SN2 SHub

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.9/arch/ia64/sn/kernel/bte.c
===================================================================
--- linux-2.6.9.orig/arch/ia64/sn/kernel/bte.c 2004-12-17 14:40:10.000000000 -0800
+++ linux-2.6.9/arch/ia64/sn/kernel/bte.c 2004-12-22 12:48:23.000000000 -0800
@@ -4,6 +4,8 @@
* for more details.
*
* Copyright (c) 2000-2003 Silicon Graphics, Inc. All Rights Reserved.
+ *
+ * Support for zeroing pages, Christoph Lameter, SGI, December 2004.
*/

#include <linux/config.h>
@@ -20,6 +22,8 @@
#include <linux/bootmem.h>
#include <linux/string.h>
#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/scrub.h>

#include <asm/sn/bte.h>

@@ -30,7 +34,7 @@
/* two interfaces on two btes */
#define MAX_INTERFACES_TO_TRY 4

-static struct bteinfo_s *bte_if_on_node(nasid_t nasid, int interface)
+static inline struct bteinfo_s *bte_if_on_node(nasid_t nasid, int interface)
{
nodepda_t *tmp_nodepda;

@@ -132,7 +136,6 @@
if (bte == NULL) {
continue;
}
-
if (spin_trylock(&bte->spinlock)) {
if (!(*bte->most_rcnt_na & BTE_WORD_AVAILABLE) ||
(BTE_LNSTAT_LOAD(bte) & BTE_ACTIVE)) {
@@ -157,7 +160,7 @@
}
} while (1);

- if (notification == NULL) {
+ if (notification == NULL || (mode & BTE_NOTIFY_AND_GET_POINTER)) {
/* User does not want to be notified. */
bte->most_rcnt_na = &bte->notify;
} else {
@@ -192,6 +195,8 @@

itc_end = ia64_get_itc() + (40000000 * local_cpu_data->cyc_per_usec);

+ if (mode & BTE_NOTIFY_AND_GET_POINTER)
+ *(u64 volatile **)(notification) = &bte->notify;
spin_unlock_irqrestore(&bte->spinlock, irq_flags);

if (notification != NULL) {
@@ -449,5 +454,37 @@
mynodepda->bte_if[i].cleanup_active = 0;
mynodepda->bte_if[i].bh_error = 0;
}
+}
+
+u64 *bte_zero_notify[MAX_COMPACT_NODES];
+
+static int bte_check_bzero(void)
+{
+ int node = get_nasid();
+
+ return *(bte_zero_notify[node]) != BTE_WORD_BUSY;
+}
+
+static int bte_start_bzero(void *p, unsigned long len)
+{
+ int node = get_nasid();
+
+ /* Check limitations.
+ 1. System must be running (weird things happen during bootup)
+ 2. Size >64KB. Smaller requests cause too much bte traffic
+ */
+ if (len >= BTE_MAX_XFER || len < 60000 || system_state != SYSTEM_RUNNING)
+ return EINVAL;
+
+ return bte_zero(ia64_tpa(p), len, BTE_NOTIFY_AND_GET_POINTER, bte_zero_notify+node);
+}
+
+static struct zero_driver bte_bzero = {
+ .start = bte_start_bzero,
+ .check = bte_check_bzero,
+ .rate = 500000000 /* 500 MB /sec */
+};

+void sn_bte_bzero_init(void) {
+ register_zero_driver(&bte_bzero);
}
Index: linux-2.6.9/arch/ia64/sn/kernel/setup.c
===================================================================
--- linux-2.6.9.orig/arch/ia64/sn/kernel/setup.c 2004-12-17 14:40:10.000000000 -0800
+++ linux-2.6.9/arch/ia64/sn/kernel/setup.c 2004-12-22 12:28:00.000000000 -0800
@@ -243,6 +243,7 @@
int pxm;
int major = sn_sal_rev_major(), minor = sn_sal_rev_minor();
extern void sn_cpu_init(void);
+ extern void sn_bte_bzero_init(void);

/*
* If the generic code has enabled vga console support - lets
@@ -333,6 +334,7 @@
screen_info = sn_screen_info;

sn_timer_init();
+ sn_bte_bzero_init();
}

/**
Index: linux-2.6.9/include/asm-ia64/sn/bte.h
===================================================================
--- linux-2.6.9.orig/include/asm-ia64/sn/bte.h 2004-12-17 14:40:16.000000000 -0800
+++ linux-2.6.9/include/asm-ia64/sn/bte.h 2004-12-22 12:28:00.000000000 -0800
@@ -48,6 +48,8 @@
#define BTE_ZERO_FILL (BTE_NOTIFY | IBCT_ZFIL_MODE)
/* Use a reserved bit to let the caller specify a wait for any BTE */
#define BTE_WACQUIRE (0x4000)
+/* Return the pointer to the notification cacheline to the user */
+#define BTE_NOTIFY_AND_GET_POINTER (0x8000)
/* Use the BTE on the node with the destination memory */
#define BTE_USE_DEST (BTE_WACQUIRE << 1)
/* Use any available BTE interface on any node for the transfer */
-
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