Messages in this thread Patch in this message | | | From | Andrew Banman <> | Subject | [PATCH] x86/platform/uv/BAU: disable BAU on single hub configurations | Date | Tue, 18 Jul 2017 16:51:33 -0500 |
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The BAU confers no benefit to a UV system running with only one hub/socket. Permanently disable the BAU driver if there are less than two hubs online to avoid BAU overhead. We have observed failed boots on single-socket UV4 systems caused by BAU that are avoided with this patch.
Signed-off-by: Andrew Banman <abanman@hpe.com> Acked-by: Russ Anderson <rja@hpe.com> Acked-by: Mike Travis <mike.travis@hpe.com> --- arch/x86/platform/uv/tlb_uv.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c index 2511a28..88216cc 100644 --- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -2251,6 +2251,12 @@ static int __init uv_bau_init(void) } nuvhubs = uv_num_possible_blades(); + if (nuvhubs < 2) { + pr_crit("UV: BAU disabled - insufficient hub count\n"); + set_bau_off(); + nobau_perm = 1; + return 0; + } uv_base_pnode = 0x7fffffff; for (uvhub = 0; uvhub < nuvhubs; uvhub++) { -- 1.8.2.1
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