Re: Increase page fault rate by prezeroing V1 [3/3]: Altix SN2 BTE Zeroing
From: Robin Holt
Date: Wed Dec 22 2004 - 07:48:10 EST
We still need to talk. This is a much smaller patch, which I like. The
problem I see in my 30 second review is you are doing things per-cpu
when they really need to be done per-node. It is very likely that
there will be M-Bricks in the system (cranberry2 has one if you want
to test your code out there or you can take any altix and disable the
cpus on a C-Brick). With M-Bricks, you will essentially limit
yourself to one zero operation per controlling node instead of one
per node.
I think the easy answer is to not have the structure allocated
within bte_copy(), but rather within bte_start_zero and passed
in as the notification address.
Give me a call sometime today (Wed. I am in the office from about
10:00 CDT until around 4:00 CDT) Maybe we can get this straightened
out quickly. If you are not calling from the office, email me with
other arrangements.
Thanks,
Robin
On Tue, Dec 21, 2004 at 11:57:57AM -0800, Christoph Lameter wrote:
> o Use the Block Transfer Engine in the Altix SN2 SHub for background zeroing
>
> 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 2004-12-21 11:03:49.000000000 -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 +34,11 @@
> /* two interfaces on two btes */
> #define MAX_INTERFACES_TO_TRY 4
>
> -static struct bteinfo_s *bte_if_on_node(nasid_t nasid, int interface)
> +DEFINE_PER_CPU(u64 *, bte_zero_notify);
> +
> +#define bte_zero_notify __get_cpu_var(bte_zero_notify)
> +
> +static inline struct bteinfo_s *bte_if_on_node(nasid_t nasid, int interface)
> {
> nodepda_t *tmp_nodepda;
>
> @@ -132,7 +140,6 @@
> 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 +164,7 @@
> }
> } 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 +199,8 @@
>
> 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 +458,31 @@
> mynodepda->bte_if[i].cleanup_active = 0;
> mynodepda->bte_if[i].bh_error = 0;
> }
> +}
> +
> +static int bte_check_bzero(void)
> +{
> + return *bte_zero_notify != BTE_WORD_BUSY;
> +}
> +
> +static int bte_start_bzero(void *p, unsigned long len)
> +{
> + /* 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);
> +}
> +
> +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 2004-12-21 11:02:35.000000000 -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 2004-12-21 11:02:35.000000000 -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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