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kvm tools: Scale guest RAM size by CPU count

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This patch increases default RAM size to 256 for one CPU and introduces RAM
size linear scaling based on CPUs as suggested by Ingo Molnar:

     64MB*(nr_cpus + 3)

     ------------------
       1 CPUs:   256 MB
       2 CPUs:   320 MB
       3 CPUs:   384 MB
       4 CPUs:   448 MB
       5 CPUs:   512 MB
       6 CPUs:   576 MB
       7 CPUs:   640 MB
       8 CPUs:   704 MB
       9 CPUs:   768 MB
      10 CPUs:   832 MB
      11 CPUs:   896 MB
      12 CPUs:   960 MB
      13 CPUs:  1024 MB
      14 CPUs:  1088 MB
      15 CPUs:  1152 MB
      16 CPUs:  1216 MB

Cc: Asias He <asias.hejun@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Prasad Joshi <prasadjoshi124@gmail.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:43 +01:00
committed by Will Deacon
parent 2449f6e369
commit fd834def0f
1 changed files with 25 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kvm-run.c
+25 -1
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@@ -46,7 +46,7 @@ static struct kvm *kvm;
static struct kvm_cpu *kvm_cpus[KVM_NR_CPUS];
static __thread struct kvm_cpu *current_kvm_cpu;
static u64 ram_size = MIN_RAM_SIZE_MB;
static u64 ram_size;
static u8 image_count;
static const char *kernel_cmdline;
static const char *kernel_filename;
@@ -213,6 +213,27 @@ static void kernel_usage_with_options(void)
fprintf(stderr, "\nPlease see 'kvm run --help' for more options.\n\n");
}
static u64 get_ram_size(int nr_cpus)
{
long available;
long page_size;
long nr_pages;
long ram_size;
ram_size = 64 * (nr_cpus + 3);
nr_pages = sysconf(_SC_PHYS_PAGES);
page_size = sysconf(_SC_PAGE_SIZE);
available = (nr_pages * page_size) >> MB_SHIFT;
if (ram_size > available)
ram_size = available;
return ram_size;
}
static const char *find_kernel(void)
{
const char **k;
@@ -330,6 +351,9 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
if (nrcpus < 1 || nrcpus > KVM_NR_CPUS)
die("Number of CPUs %d is out of [1;%d] range", nrcpus, KVM_NR_CPUS);
if (!ram_size)
ram_size = get_ram_size(nrcpus);
if (ram_size < MIN_RAM_SIZE_MB)
die("Not enough memory specified: %lluMB (min %lluMB)", ram_size, MIN_RAM_SIZE_MB);