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[Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splittin
From: |
Igor Mammedov |
Subject: |
[Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions |
Date: |
Tue, 29 Oct 2013 19:18:49 +0100 |
Otherwise 1GB TLBs cannot be cached for the range.
PS:
as side effect we are not wasting ~1Gb of memory if
1Gb hugepages are used and -m "hpagesize(in Mb)*n + 1"
Signed-off-by: Igor Mammedov <address@hidden>
---
PS2:
As RFC it's yet without compatibility changes noted by Paolo
---
exec.c | 8 ++++++-
hw/i386/pc.c | 50 ++++++++++++++++++++++++++++----------------
include/exec/cpu-common.h | 1 +
3 files changed, 40 insertions(+), 19 deletions(-)
diff --git a/exec.c b/exec.c
index 9b6ea50..a4e5c80 100644
--- a/exec.c
+++ b/exec.c
@@ -882,7 +882,7 @@ void qemu_mutex_unlock_ramlist(void)
#define HUGETLBFS_MAGIC 0x958458f6
-static long gethugepagesize(const char *path)
+long gethugepagesize(const char *path)
{
struct statfs fs;
int ret;
@@ -925,6 +925,12 @@ static void *file_ram_alloc(RAMBlock *block,
return NULL;
}
+ /* refuse to use huge pages if requested size isn't page aligned
+ * to avoid wasting memory */
+ if (memory != (memory & ~(hpagesize-1))) {
+ return NULL;
+ }
+
if (kvm_enabled() && !kvm_has_sync_mmu()) {
fprintf(stderr, "host lacks kvm mmu notifiers, -mem-path
unsupported\n");
return NULL;
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 0c313fe..1611fa7 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1116,32 +1116,46 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
{
int linux_boot, i;
MemoryRegion *ram, *option_rom_mr;
- MemoryRegion *ram_below_4g, *ram_above_4g;
FWCfgState *fw_cfg;
+ unsigned long hpagesize = gethugepagesize(mem_path);
+ ram_addr_t below_4g_mem_size_alined, below_4g_mem_size_tail,
above_4g_mem_size_alined, above_4g_mem_size_tail;
linux_boot = (kernel_filename != NULL);
- /* Allocate RAM. We allocate it as a single memory region and use
- * aliases to address portions of it, mostly for backwards compatibility
- * with older qemus that used qemu_ram_alloc().
- */
+ *ram_memory = g_malloc(sizeof(**ram_memory));
+ memory_region_init(*ram_memory, NULL, "pc.ram",
+ above_4g_mem_size == 0 ? below_4g_mem_size:
0x100000000ULL + above_4g_mem_size);
+ memory_region_add_subregion(system_memory, 0, *ram_memory);
+
+ below_4g_mem_size_alined = below_4g_mem_size & ~(hpagesize - 1);
ram = g_malloc(sizeof(*ram));
- memory_region_init_ram(ram, NULL, "pc.ram",
- below_4g_mem_size + above_4g_mem_size);
+ memory_region_init_ram(ram, NULL, "pc.ram.low.aligned",
below_4g_mem_size_alined);
+ memory_region_add_subregion(*ram_memory, 0, ram);
vmstate_register_ram_global(ram);
- *ram_memory = ram;
- ram_below_4g = g_malloc(sizeof(*ram_below_4g));
- memory_region_init_alias(ram_below_4g, NULL, "ram-below-4g", ram,
- 0, below_4g_mem_size);
- memory_region_add_subregion(system_memory, 0, ram_below_4g);
- if (above_4g_mem_size > 0) {
- ram_above_4g = g_malloc(sizeof(*ram_above_4g));
- memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g", ram,
- below_4g_mem_size, above_4g_mem_size);
- memory_region_add_subregion(system_memory, 0x100000000ULL,
- ram_above_4g);
+
+ below_4g_mem_size_tail = below_4g_mem_size - below_4g_mem_size_alined;
+ if (below_4g_mem_size_tail) {
+ ram = g_malloc(sizeof(*ram));
+ memory_region_init_ram(ram, NULL, "pc.ram.low.unaligned",
below_4g_mem_size_tail);
+ memory_region_add_subregion(*ram_memory, below_4g_mem_size_alined,
ram);
+ vmstate_register_ram_global(ram);
}
+ if (above_4g_mem_size > 0) {
+ above_4g_mem_size_alined = above_4g_mem_size & ~(hpagesize - 1);
+ ram = g_malloc(sizeof(*ram));
+ memory_region_init_ram(ram, NULL, "pc.ram.high.aligned",
above_4g_mem_size_alined);
+ memory_region_add_subregion(*ram_memory, 0x100000000ULL, ram);
+ vmstate_register_ram_global(ram);
+
+ above_4g_mem_size_tail = above_4g_mem_size - above_4g_mem_size_alined;
+ if (above_4g_mem_size_tail) {
+ ram = g_malloc(sizeof(*ram));
+ memory_region_init_ram(ram, NULL, "pc.ram.high.unaligned",
above_4g_mem_size_tail);
+ memory_region_add_subregion(*ram_memory, 0x100000000ULL +
above_4g_mem_size_alined, ram);
+ vmstate_register_ram_global(ram);
+ }
+ }
/* Initialize PC system firmware */
pc_system_firmware_init(rom_memory, guest_info->isapc_ram_fw);
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 40e15e4..f89a37c 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -57,6 +57,7 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name,
DeviceState *dev);
#ifdef __linux__
uint32_t qemu_get_ram_hpagesize(ram_addr_t addr);
#endif
+long gethugepagesize(const char *path);
void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
int len, int is_write);
--
1.7.1
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, (continued)
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Paolo Bonzini, 2013/10/30
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, igor Mammedov, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, igor Mammedov, 2013/10/27
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/28
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/28
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Igor Mammedov, 2013/10/29
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/29
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Gleb Natapov, 2013/10/30
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/30
- [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions,
Igor Mammedov <=
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Marcelo Tosatti, 2013/10/29
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Igor Mammedov, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Marcelo Tosatti, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Marcelo Tosatti, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Igor Mammedov, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Marcelo Tosatti, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Marcelo Tosatti, 2013/10/30
- Re: [Qemu-devel] [RFC PATCH] pc: align gpa<->hpa on 1GB boundary by splitting RAM on several regions, Paolo Bonzini, 2013/10/30