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Commit 90cc7d94 authored by Cliff Wickman's avatar Cliff Wickman Committed by Ingo Molnar
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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: default avatarCliff Wickman <cpw@sgi.com>
Cc: gregkh@suse.de
LKML-Reference: <E1OJvNy-0004ad-BV@eag09.americas.sgi.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a8328ee5

arch/x86/include/asm/uv/uv_bau.h

+0 −1
Original line number Diff line number Diff line
@@ -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 */

arch/x86/kernel/tlb_uv.c

+0 −23
Original line number Diff line number Diff line
@@ -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);