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Subject[PATCH 3/5] ia64: Reduce stack usage by iterating over nodemask
Date
GCC complains about sn2_global_tlb_purge() because of the large stack
required by the function,

arch/ia64/sn/kernel/sn2/sn2_smp.c: In function 'sn2_global_tlb_purge':
arch/ia64/sn/kernel/sn2/sn2_smp.c:319:1: warning: the frame size of 2176 bytes is larger than 2048 bytes [-Wframe-larger-than=]

2048 bytes of the stack are consumed by the node ID array 'nasids[]'.
But we don't actually need to put the ID array on the stack and can
use nodemask operations.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
arch/ia64/sn/kernel/sn2/sn2_smp.c | 35 +++++++++++++++++++++++------------
1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c
index f9c8d9fc5939..c98dc965fe82 100644
--- a/arch/ia64/sn/kernel/sn2/sn2_smp.c
+++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c
@@ -54,7 +54,7 @@ sn2_ptc_deadlock_recovery_core(volatile unsigned long *, unsigned long,
volatile unsigned long *, unsigned long,
volatile unsigned long *, unsigned long);
void
-sn2_ptc_deadlock_recovery(short *, short, short, int,
+sn2_ptc_deadlock_recovery(nodemask_t, short, short, int,
volatile unsigned long *, unsigned long,
volatile unsigned long *, unsigned long);

@@ -169,7 +169,7 @@ sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
int use_cpu_ptcga;
volatile unsigned long *ptc0, *ptc1;
unsigned long itc, itc2, flags, data0 = 0, data1 = 0, rr_value, old_rr = 0;
- short nasids[MAX_NUMNODES], nix;
+ short nix;
nodemask_t nodes_flushed;
int active, max_active, deadlock, flush_opt = sn2_flush_opt;

@@ -218,9 +218,7 @@ sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
}

itc = ia64_get_itc();
- nix = 0;
- for_each_node_mask(cnode, nodes_flushed)
- nasids[nix++] = cnodeid_to_nasid(cnode);
+ nix = nodes_weight(nodes_flushed);

rr_value = (mm->context << 3) | REGION_NUMBER(start);

@@ -270,8 +268,10 @@ sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
data0 = (data0 & ~SH2_PTC_ADDR_MASK) | (start & SH2_PTC_ADDR_MASK);
deadlock = 0;
active = 0;
- for (ibegin = 0, i = 0; i < nix; i++) {
- nasid = nasids[i];
+ ibegin = 0;
+ i = 0;
+ for_each_node_mask(cnode, nodes_flushed) {
+ nasid = cnodeid_to_nasid(cnode);
if (use_cpu_ptcga && unlikely(nasid == mynasid)) {
ia64_ptcga(start, nbits << 2);
ia64_srlz_i();
@@ -286,13 +286,14 @@ sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
if ((deadlock = wait_piowc())) {
if (flush_opt == 1)
goto done;
- sn2_ptc_deadlock_recovery(nasids, ibegin, i, mynasid, ptc0, data0, ptc1, data1);
+ sn2_ptc_deadlock_recovery(nodes_flushed, ibegin, i, mynasid, ptc0, data0, ptc1, data1);
if (reset_max_active_on_deadlock())
max_active = 1;
}
active = 0;
ibegin = i + 1;
}
+ i++;
}
start += (1UL << nbits);
} while (start < end);
@@ -327,11 +328,12 @@ done:
*/

void
-sn2_ptc_deadlock_recovery(short *nasids, short ib, short ie, int mynasid,
+sn2_ptc_deadlock_recovery(nodemask_t nodes, short ib, short ie, int mynasid,
volatile unsigned long *ptc0, unsigned long data0,
volatile unsigned long *ptc1, unsigned long data1)
{
short nasid, i;
+ int cnode;
unsigned long *piows, zeroval, n;

__this_cpu_inc(ptcstats.deadlocks);
@@ -339,17 +341,26 @@ sn2_ptc_deadlock_recovery(short *nasids, short ib, short ie, int mynasid,
piows = (unsigned long *) pda->pio_write_status_addr;
zeroval = pda->pio_write_status_val;

+ i = 0;
+ for_each_node_mask(cnode, nodes) {
+ if (i < ib)
+ goto next;
+
+ if (i > ie)
+ break;

- for (i=ib; i <= ie; i++) {
- nasid = nasids[i];
+ nasid = cnodeid_to_nasid(cnode);
if (local_node_uses_ptc_ga(is_shub1()) && nasid == mynasid)
- continue;
+ goto next;
+
ptc0 = CHANGE_NASID(nasid, ptc0);
if (ptc1)
ptc1 = CHANGE_NASID(nasid, ptc1);

n = sn2_ptc_deadlock_recovery_core(ptc0, data0, ptc1, data1, piows, zeroval);
__this_cpu_add(ptcstats.deadlocks2, n);
+next:
+ i++;
}

}
--
2.7.3
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