Messages in this thread | | | Date | Wed, 22 Dec 2004 06:46:48 -0600 | From | Robin Holt <> | Subject | Re: Increase page fault rate by prezeroing V1 [3/3]: Altix SN2 BTE Zeroing |
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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 */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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