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s390/smp: limit number of cpus in possible cpu mask

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Limit the number of bits to the maximum number of cpus a machine
can have.
possible_cpu_mask typically will have more bits set than a machine
may physically have. This results in wasted memory during per-cpu
memory allocations, if the possible mask contains more cpus than
physically possible for a given configuration.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2014-03-10 14:50:16 +01:00 committed by Martin Schwidefsky
parent 36a554021b
commit cf813db0b4
3 changed files with 26 additions and 6 deletions
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1
arch/s390/include/asm/sclp.h
View File

@ -46,6 +46,7 @@ int sclp_cpu_configure(u8 cpu);
int sclp_cpu_deconfigure(u8 cpu);
unsigned long long sclp_get_rnmax(void);
unsigned long long sclp_get_rzm(void);
unsigned int sclp_get_max_cpu(void);
int sclp_sdias_blk_count(void);
int sclp_sdias_copy(void *dest, int blk_num, int nr_blks);
int sclp_chp_configure(struct chp_id chpid);

8
arch/s390/kernel/smp.c
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@ -773,11 +773,11 @@ void __noreturn cpu_die(void)
void __init smp_fill_possible_mask(void)
{
unsigned int possible, cpu;
unsigned int possible, sclp, cpu;
possible = setup_possible_cpus;
if (!possible)
possible = MACHINE_IS_VM ? 64 : nr_cpu_ids;
sclp = sclp_get_max_cpu() ?: nr_cpu_ids;
possible = setup_possible_cpus ?: nr_cpu_ids;
possible = min(possible, sclp);
for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
set_cpu_possible(cpu, true);
}

23
drivers/s390/char/sclp_early.c
View File

@ -20,7 +20,9 @@ struct read_info_sccb {
struct sccb_header header; /* 0-7 */
u16 rnmax; /* 8-9 */
u8 rnsize; /* 10 */
u8 _reserved0[24 - 11]; /* 11-15 */
u8 _reserved0[16 - 11]; /* 11-15 */
u16 ncpurl; /* 16-17 */
u8 _reserved7[24 - 18]; /* 18-23 */
u8 loadparm[8]; /* 24-31 */
u8 _reserved1[48 - 32]; /* 32-47 */
u64 facilities; /* 48-55 */
@ -32,13 +34,16 @@ struct read_info_sccb {
u8 _reserved4[100 - 92]; /* 92-99 */
u32 rnsize2; /* 100-103 */
u64 rnmax2; /* 104-111 */
u8 _reserved5[4096 - 112]; /* 112-4095 */
u8 _reserved5[120 - 112]; /* 112-119 */
u16 hcpua; /* 120-121 */
u8 _reserved6[4096 - 122]; /* 122-4095 */
} __packed __aligned(PAGE_SIZE);
static char sccb_early[PAGE_SIZE] __aligned(PAGE_SIZE) __initdata;
static unsigned int sclp_con_has_vt220 __initdata;
static unsigned int sclp_con_has_linemode __initdata;
static unsigned long sclp_hsa_size;
static unsigned int sclp_max_cpu;
static struct sclp_ipl_info sclp_ipl_info;
u64 sclp_facilities;
@ -102,6 +107,15 @@ static void __init sclp_facilities_detect(struct read_info_sccb *sccb)
sclp_rzm = sccb->rnsize ? sccb->rnsize : sccb->rnsize2;
sclp_rzm <<= 20;
if (!sccb->hcpua) {
if (MACHINE_IS_VM)
sclp_max_cpu = 64;
else
sclp_max_cpu = sccb->ncpurl;
} else {
sclp_max_cpu = sccb->hcpua + 1;
}
/* Save IPL information */
sclp_ipl_info.is_valid = 1;
if (sccb->flags & 0x2)
@ -129,6 +143,11 @@ unsigned long long sclp_get_rzm(void)
return sclp_rzm;
}
unsigned int sclp_get_max_cpu(void)
{
return sclp_max_cpu;
}
/*
* This function will be called after sclp_facilities_detect(), which gets
* called from early.c code. The sclp_facilities_detect() function retrieves