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[IA64] Kernel parameter for max number of concurrent global TLB purges

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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
SAL PALO.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Fenghua Yu
2008-03-14 13:57:08 -07:00
committed by Tony Luck
parent 2046b94e7c
commit a6c75b86ce
5 changed files with 51 additions and 7 deletions
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46
arch/ia64/mm/tlb.c
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@ -119,6 +119,27 @@ static u16 nptcg = 1;
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
@ -126,13 +147,18 @@ static int toolatetochangeptcgsem = 0;
* 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;