Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756639AbcCaTSd (ORCPT ); Thu, 31 Mar 2016 15:18:33 -0400 Received: from relay1.sgi.com ([192.48.180.66]:42016 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752446AbcCaTSc (ORCPT ); Thu, 31 Mar 2016 15:18:32 -0400 From: Alex Thorlton To: linux-kernel@vger.kernel.org Cc: Alex Thorlton , Hedi Berriche , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jonathan Corbet , x86@kernel.org Subject: [PATCH v2] x86/platform/uv: Disable UV BAU by default Date: Thu, 31 Mar 2016 14:18:29 -0500 Message-Id: <1459451909-121845-1-git-send-email-athorlton@sgi.com> X-Mailer: git-send-email 1.8.5.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4518 Lines: 150 For several years, the common practice has been to boot UVs with the "nobau" parameter on the command line, to disable the BAU. We've decided that it makes more sense to just disable the BAU by default in the kernel, and provide the option to turn it on, if desired. For now, having the on/off switch doesn't buy us any more than just reversing the logic would, but we're working towards having the BAU enabled by default on UV4. When those changes are in place, having the on/off switch will make more sense than an enable flag, since the default behavior will be different depending on the system version. I've also added a bit of documentation for the new parameter to Documentation/kernel-parameters.txt. Signed-off-by: Alex Thorlton Reviewed-by: Hedi Berriche Cc: Hedi Berriche Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Jonathan Corbet Cc: x86@kernel.org --- Documentation/kernel-parameters.txt | 8 ++++++++ arch/x86/include/asm/uv/uv_bau.h | 2 +- arch/x86/platform/uv/tlb_uv.c | 35 +++++++++++++++++++++++++---------- 3 files changed, 34 insertions(+), 11 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index def4791..611247b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -131,6 +131,7 @@ parameter is applicable: More X86-64 boot options can be found in Documentation/x86/x86_64/boot-options.txt . X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) + X86_UV SGI UV support is enabled. XEN Xen support is enabled In addition, the following text indicates that the option: @@ -542,6 +543,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: (must be >=0) Default: 64 + bau= [X86_UV] Enable the BAU on SGI UV. The default + behavior is to disable the BAU (i.e. bau=0). + Format: { "0" | "1" } + 0 - Disable the BAU. + 1 - Enable the BAU. + unset - Disable the BAU. + baycom_epp= [HW,AX25] Format: , diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h index fc808b8..cc44d92 100644 --- a/arch/x86/include/asm/uv/uv_bau.h +++ b/arch/x86/include/asm/uv/uv_bau.h @@ -598,7 +598,7 @@ struct bau_control { int timeout_tries; int ipi_attempts; int conseccompletes; - short nobau; + bool nobau; short baudisabled; short cpu; short osnode; diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c index 3b6ec42..534ab94 100644 --- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -37,7 +37,7 @@ static int timeout_base_ns[] = { }; static int timeout_us; -static int nobau; +static bool nobau = true; static int nobau_perm; static cycles_t congested_cycles; @@ -106,13 +106,28 @@ static char *stat_description[] = { "enable: number times use of the BAU was re-enabled" }; -static int __init -setup_nobau(char *arg) +static int __init setup_bau(char *arg) { - nobau = 1; + int result; + + if (!arg) + return -EINVAL; + + result = strtobool(arg, &nobau); + if (result) + return result; + + /* we need to flip the logic here, so that bau=y sets nobau to false */ + nobau = !nobau; + + if (!nobau) + pr_info("UV BAU Enabled\n"); + else + pr_info("UV BAU Disabled\n"); + return 0; } -early_param("nobau", setup_nobau); +early_param("bau", setup_bau); /* base pnode in this partition */ static int uv_base_pnode __read_mostly; @@ -131,10 +146,10 @@ set_bau_on(void) pr_info("BAU not initialized; cannot be turned on\n"); return; } - nobau = 0; + nobau = false; for_each_present_cpu(cpu) { bcp = &per_cpu(bau_control, cpu); - bcp->nobau = 0; + bcp->nobau = false; } pr_info("BAU turned on\n"); return; @@ -146,10 +161,10 @@ set_bau_off(void) int cpu; struct bau_control *bcp; - nobau = 1; + nobau = true; for_each_present_cpu(cpu) { bcp = &per_cpu(bau_control, cpu); - bcp->nobau = 1; + bcp->nobau = true; } pr_info("BAU turned off\n"); return; @@ -1886,7 +1901,7 @@ static void __init init_per_cpu_tunables(void) bcp = &per_cpu(bau_control, cpu); bcp->baudisabled = 0; if (nobau) - bcp->nobau = 1; + bcp->nobau = true; bcp->statp = &per_cpu(ptcstats, cpu); /* time interval to catch a hardware stay-busy bug */ bcp->timeout_interval = usec_2_cycles(2*timeout_us); -- 1.8.5.6