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s390/mem_detect: replace tprot loop with binary search

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In a situation when other memory detection methods are not available
(no SCLP and no z/VM diag260), continuous online memory is assumed.
Replacing tprot loop with faster binary search, as only online memory
end has to be found.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Vasily Gorbik
2018-04-11 19:15:24 +02:00
committed by Martin Schwidefsky
parent cd45c99561
commit 54c57795e8
4 changed files with 18 additions and 34 deletions
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45
arch/s390/boot/mem_detect.c
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@@ -3,12 +3,10 @@
#include <asm/sclp.h>
#include <asm/sections.h>
#include <asm/mem_detect.h>
#include <asm/sparsemem.h>
#include "compressed/decompressor.h"
#include "boot.h"
#define CHUNK_READ_WRITE 0
#define CHUNK_READ_ONLY 1
unsigned long __bootdata(max_physmem_end);
struct mem_detect_info __bootdata(mem_detect);
@@ -141,38 +139,25 @@ static int tprot(unsigned long addr)
return rc;
}
static void scan_memory(unsigned long rzm)
static void search_mem_end(void)
{
unsigned long addr, size;
int type;
unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
unsigned long offset = 0;
unsigned long pivot;
if (!rzm)
rzm = 1UL << 20;
while (range > 1) {
range >>= 1;
pivot = offset + range;
if (!tprot(pivot << 20))
offset = pivot;
}
addr = 0;
do {
size = 0;
/* assume lowcore is writable */
type = addr ? tprot(addr) : CHUNK_READ_WRITE;
do {
size += rzm;
if (max_physmem_end && addr + size >= max_physmem_end)
break;
} while (type == tprot(addr + size));
if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
if (max_physmem_end && (addr + size > max_physmem_end))
size = max_physmem_end - addr;
add_mem_detect_block(addr, addr + size);
}
addr += size;
} while (addr < max_physmem_end);
add_mem_detect_block(0, (offset + 1) << 20);
}
void detect_memory(void)
{
unsigned long rzm;
sclp_early_get_meminfo(&max_physmem_end, &rzm);
sclp_early_get_memsize(&max_physmem_end);
if (!sclp_early_read_storage_info()) {
mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
@@ -190,7 +175,7 @@ void detect_memory(void)
return;
}
scan_memory(rzm);
mem_detect.info_source = MEM_DETECT_TPROT_LOOP;
search_mem_end();
mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
max_physmem_end = get_mem_detect_end();
}