On 11/19/20 9:41 AM, Thomas Huth wrote:
> On 17/11/2020 16.42, Janosch Frank wrote:
>> Let's only read the information once and pass a pointer to it instead
>> of calling sclp multiple times.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>> lib/s390x/io.c | 1 +
>> lib/s390x/sclp.c | 29 +++++++++++++++++++++++------
>> lib/s390x/sclp.h | 3 +++
>> lib/s390x/smp.c | 23 +++++++++--------------
>> 4 files changed, 36 insertions(+), 20 deletions(-)
>>
>> diff --git a/lib/s390x/io.c b/lib/s390x/io.c
>> index c0f0bf7..e19a1f3 100644
>> --- a/lib/s390x/io.c
>> +++ b/lib/s390x/io.c
>> @@ -36,6 +36,7 @@ void setup(void)
>> {
>> setup_args_progname(ipl_args);
>> setup_facilities();
>> + sclp_read_info();
>> sclp_console_setup();
>> sclp_memory_setup();
>> smp_setup();
>> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
>> index 4054d0e..ea6324e 100644
>> --- a/lib/s390x/sclp.c
>> +++ b/lib/s390x/sclp.c
>> @@ -25,6 +25,8 @@ extern unsigned long stacktop;
>> static uint64_t storage_increment_size;
>> static uint64_t max_ram_size;
>> static uint64_t ram_size;
>> +char _read_info[PAGE_SIZE] __attribute__((__aligned__(4096)));
>> +static ReadInfo *read_info;
>>
>> char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
>> static volatile bool sclp_busy;
>> @@ -110,6 +112,22 @@ static void sclp_read_scp_info(ReadInfo *ri, int length)
>> report_abort("READ_SCP_INFO failed");
>> }
>>
>> +void sclp_read_info(void)
>> +{
>> + sclp_read_scp_info((void *)_read_info, SCCB_SIZE);
>> + read_info = (ReadInfo *)_read_info;
>> +}
>> +
>> +int sclp_get_cpu_num(void)
>> +{
>> + return read_info->entries_cpu;
>> +}
> [...]
>> int smp_query_num_cpus(void)
>> {
>> - struct ReadCpuInfo *info = (void *)cpu_info_buffer;
>> - return info->nr_configured;
>> + return sclp_get_cpu_num();
>> }
>
> You've changed from ->nr_configured to ->entries_cpu ... I assume that's ok?
> Worth to mention the change and rationale in the patch description?
Well, it's not so much a change of struct members than a change of
structs themselves. Looking at our QEMU implementation, both struct
members transport the same data so I don't see a problem there.
>
>> struct cpu *smp_cpu_from_addr(uint16_t addr)
>> @@ -245,22 +244,18 @@ extern uint64_t *stackptr;
>> void smp_setup(void)
>> {
>> int i = 0;
>> + int num = smp_query_num_cpus();
>> unsigned short cpu0_addr = stap();
>> - struct ReadCpuInfo *info = (void *)cpu_info_buffer;
>> + struct CPUEntry *entry = sclp_get_cpu_entries();
>>
>> - spin_lock(&lock);
>> - sclp_mark_busy();
>> - info->h.length = PAGE_SIZE;
>> - sclp_service_call(SCLP_READ_CPU_INFO, cpu_info_buffer);
>> + if (num > 1)
>> + printf("SMP: Initializing, found %d cpus\n", num);
>>
>> - if (smp_query_num_cpus() > 1)
>> - printf("SMP: Initializing, found %d cpus\n", info->nr_configured);
>> -
>> - cpus = calloc(info->nr_configured, sizeof(cpus));
>> - for (i = 0; i < info->nr_configured; i++) {
>> - cpus[i].addr = info->entries[i].address;
>> + cpus = calloc(num, sizeof(cpus));
>> + for (i = 0; i < num; i++) {
>> + cpus[i].addr = entry[i].address;
>> cpus[i].active = false;
>> - if (info->entries[i].address == cpu0_addr) {
>> + if (entry[i].address == cpu0_addr) {
>> cpu0 = &cpus[i];
>> cpu0->stack = stackptr;
>> cpu0->lowcore = (void *)0;
>>
>
> What about smp_teardown()? It seems to use cpu_info_buffer->nr_configured,
> too, which is now likely not valid anymore?
Good catch, I forgot to remove the whole cpu info buffer.
>
> Thomas
>
