From: Luming Yu <luyu@redhat.com> Date: Sat, 13 Sep 2008 00:48:34 +0800 Subject: [ia64] param for max num of concurrent global TLB purges Message-id: 48CA9D62.8070400@redhat.com O-Subject: Re: [RHEL 5.3 PATCH 2/2] bz 451593: Kernel parameter for max number of concurrent global TLB purges Bugzilla: 451593 RH-Acked-by: Prarit Bhargava <prarit@redhat.com> bz 451593 Description of problem: The patch defines kernel parameter "nptcg=". The parameter overrides max number of concurrent global TLB purges which is reported from either PAL_VM_SUMMARY or Upstream status: a6c75b86ce9f01db4ea9912877b526c2dc4d2f0a Testing status: Boot fine on tiger4 and Cold fusion, and nothing unusual found. I don't have box with PALO table to support this feature to test this feature right now. Update the patch series against -105 kernel. And add one more patch to set max_purges=1 by default regardless what PAL returns to make sure no regressions. Please revew and ACKs. NOTE: to apply, please keep it in this order: 1. [RHEL 5.3 PATCH 1/2] bz 451593: Multiple outstanding ptc.g instruction support 2. [RHEL 5.3 PATCH 2/2] bz 451593: Kernel parameter for max number of concurrent global TLB purges 3. [RHEL 5.3 PATCH 1/1] bz 451593: set max_purges=1 by default regardless what PAL returns Thanks, Luming diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c index 35b3d22..c4f7237 100644 --- a/arch/ia64/kernel/efi.c +++ b/arch/ia64/kernel/efi.c @@ -418,7 +418,7 @@ static void __init handle_palo(unsigned long palo_phys) return; } - setup_ptcg_sem(palo->max_tlb_purges, 1); + setup_ptcg_sem(palo->max_tlb_purges, NPTCG_FROM_PALO); } void diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c index 5e8704a..3e8b5f8 100644 --- a/arch/ia64/kernel/setup.c +++ b/arch/ia64/kernel/setup.c @@ -1069,7 +1069,7 @@ cpu_init (void) /* set ia64_ctx.max_rid to the maximum RID that is supported by all CPUs: */ if (ia64_pal_vm_summary(NULL, &vmi) == 0) { max_ctx = (1U << (vmi.pal_vm_info_2_s.rid_size - 3)) - 1; - setup_ptcg_sem(vmi.pal_vm_info_2_s.max_purges, 0); + setup_ptcg_sem(vmi.pal_vm_info_2_s.max_purges, NPTCG_FROM_PAL); } else { printk(KERN_WARNING "cpu_init: PAL VM summary failed, assuming 18 RID bits\n"); max_ctx = (1U << 15) - 1; /* use architected minimum */ diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c index c3b3994..f854597 100644 --- a/arch/ia64/mm/tlb.c +++ b/arch/ia64/mm/tlb.c @@ -120,19 +120,45 @@ static int need_ptcg_sem = 1; static int toolatetochangeptcgsem = 0; /* + * Kernel parameter "nptcg=" overrides max number of concurrent global TLB + * purges which is reported from either PAL or SAL PALO. + * + * We don't have sanity checking for nptcg value. It's the user's responsibility + * for valid nptcg value on the platform. Otherwise, kernel may hang in some + * cases. + */ +static int __init +set_nptcg(char *str) +{ + int value = 0; + + get_option(&str, &value); + setup_ptcg_sem(value, NPTCG_FROM_KERNEL_PARAMETER); + + return 1; +} + +__setup("nptcg=", set_nptcg); + +/* * Maximum number of simultaneous ptc.g purges in the system can * be defined by PAL_VM_SUMMARY (in which case we should take * the smallest value for any cpu in the system) or by the PAL * override table (in which case we should ignore the value from * PAL_VM_SUMMARY). * + * Kernel parameter "nptcg=" overrides maximum number of simultanesous ptc.g + * purges defined in either PAL_VM_SUMMARY or PAL override table. In this case, + * we should ignore the value from either PAL_VM_SUMMARY or PAL override table. + * * Complicating the logic here is the fact that num_possible_cpus() * isn't fully setup until we start bringing cpus online. */ void -setup_ptcg_sem(int max_purges, int from_palo) +setup_ptcg_sem(int max_purges, int nptcg_from) { - static int have_palo; + static int kp_override; + static int palo_override; static int firstcpu = 1; if (toolatetochangeptcgsem) { @@ -140,8 +166,18 @@ setup_ptcg_sem(int max_purges, int from_palo) return; } - if (from_palo) { - have_palo = 1; + if (nptcg_from == NPTCG_FROM_KERNEL_PARAMETER) { + kp_override = 1; + nptcg = max_purges; + goto resetsema; + } + if (kp_override) { + need_ptcg_sem = num_possible_cpus() > nptcg; + return; + } + + if (nptcg_from == NPTCG_FROM_PALO) { + palo_override = 1; /* In PALO max_purges == 0 really means it! */ if (max_purges == 0) @@ -153,7 +189,7 @@ setup_ptcg_sem(int max_purges, int from_palo) } goto resetsema; } - if (have_palo) { + if (palo_override) { if (nptcg != PALO_MAX_TLB_PURGES) need_ptcg_sem = (num_possible_cpus() > nptcg); return; diff --git a/include/asm-ia64/sal.h b/include/asm-ia64/sal.h index 50eb9d3..863ca56 100644 --- a/include/asm-ia64/sal.h +++ b/include/asm-ia64/sal.h @@ -920,6 +920,10 @@ struct palo_table { u8 reserved2[6]; }; +#define NPTCG_FROM_PAL 0 +#define NPTCG_FROM_PALO 1 +#define NPTCG_FROM_KERNEL_PARAMETER 2 + #endif /* __ASSEMBLY__ */ #endif /* _ASM_IA64_SAL_H */