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Subject[tip:x86/uv] x86, UV: Remove BAU check for stay-busy
Commit-ID:  90cc7d944981a6d06b49bb26fde1b490e28c90e5
Gitweb: http://git.kernel.org/tip/90cc7d944981a6d06b49bb26fde1b490e28c90e5
Author: Cliff Wickman <cpw@sgi.com>
AuthorDate: Wed, 2 Jun 2010 16:22:02 -0500
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 8 Jun 2010 21:13:47 +0200

x86, UV: Remove BAU check for stay-busy

Remove a faulty assumption that a long running BAU request has
encountered a hardware problem and will never finish.

Numalink congestion can make a request appear to have
encountered such a problem, but it is not safe to cancel the
request. If such a cancel is done but a reply is later received
we can miss a TLB shootdown.

We depend upon the max_bau_concurrent 'throttle' to prevent the
stay-busy case from happening.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: gregkh@suse.de
LKML-Reference: <E1OJvNy-0004ad-BV@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/include/asm/uv/uv_bau.h | 1 -
arch/x86/kernel/tlb_uv.c | 23 -----------------------
2 files changed, 0 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h
index 1c8f1e9..c19b870 100644
--- a/arch/x86/include/asm/uv/uv_bau.h
+++ b/arch/x86/include/asm/uv/uv_bau.h
@@ -402,7 +402,6 @@ struct bau_control {
unsigned short uvhub_quiesce;
short socket_acknowledge_count[DEST_Q_SIZE];
cycles_t send_message;
- spinlock_t masks_lock;
spinlock_t uvhub_lock;
spinlock_t queue_lock;
/* tunables */
diff --git a/arch/x86/kernel/tlb_uv.c b/arch/x86/kernel/tlb_uv.c
index ab929e9..dc962b5 100644
--- a/arch/x86/kernel/tlb_uv.c
+++ b/arch/x86/kernel/tlb_uv.c
@@ -405,12 +405,10 @@ static int uv_wait_completion(struct bau_desc *bau_desc,
unsigned long mmr;
unsigned long mask;
cycles_t ttime;
- cycles_t timeout_time;
struct ptc_stats *stat = bcp->statp;
struct bau_control *hmaster;

hmaster = bcp->uvhub_master;
- timeout_time = get_cycles() + bcp->timeout_interval;

/* spin on the status MMR, waiting for it to go idle */
while ((descriptor_status = (((unsigned long)
@@ -450,26 +448,6 @@ static int uv_wait_completion(struct bau_desc *bau_desc,
* descriptor_status is still BUSY
*/
cpu_relax();
- relaxes++;
- if (relaxes >= 10000) {
- relaxes = 0;
- if (get_cycles() > timeout_time) {
- quiesce_local_uvhub(hmaster);
-
- /* single-thread the register change */
- spin_lock(&hmaster->masks_lock);
- mmr = uv_read_local_mmr(mmr_offset);
- mask = 0UL;
- mask |= (3UL < right_shift);
- mask = ~mask;
- mmr &= mask;
- uv_write_local_mmr(mmr_offset, mmr);
- spin_unlock(&hmaster->masks_lock);
- end_uvhub_quiesce(hmaster);
- stat->s_busy++;
- return FLUSH_GIVEUP;
- }
- }
}
}
bcp->conseccompletes++;
@@ -1580,7 +1558,6 @@ static void uv_init_per_cpu(int nuvhubs)
for_each_present_cpu(cpu) {
bcp = &per_cpu(bau_control, cpu);
memset(bcp, 0, sizeof(struct bau_control));
- spin_lock_init(&bcp->masks_lock);
pnode = uv_cpu_hub_info(cpu)->pnode;
uvhub = uv_cpu_hub_info(cpu)->numa_blade_id;
uvhub_mask |= (1 << uvhub);

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