diff options
| author | Michael Holzheu <holzheu@linux.vnet.ibm.com> | 2015-10-30 16:02:04 +0100 |
|---|---|---|
| committer | Simon Horman <horms@verge.net.au> | 2015-11-09 10:58:53 +0900 |
| commit | 95741713e790fa6bde7780bbfb772ad88e81a744 (patch) | |
| tree | ee32757b0773ee921605002ecfb88d736b189edb /kexec/arch | |
| parent | 8d8c6bcee59306482d86d7c524f511a08ad02de6 (diff) | |
kexec/s390x: use mmap instead of read for slurp_file()
The slurp_fd() function allocates memory and uses the read() system call.
This results in double memory consumption for image and initrd:
1) Memory allocated in user space by the kexec tool
2) Memory allocated in kernel by the kexec() system call
The following illustrates the use case that we have on s390x:
1) Boot a 4 GB Linux system
2) Copy kernel and 1,5 GB ramdisk from external source into tmpfs (ram)
3) Use kexec to boot kernel with ramdisk
Therefore for kexec runtime we need:
1,5 GB (tmpfs) + 1,5 GB (kexec malloc) + 1,5 GB (kernel memory) = 4,5 GB
This patch introduces slurp_file_mmap() which for "normal" files uses
mmap() instead of malloc()/read(). This reduces the runtime memory
consumption of the kexec tool as follows:
1,5 GB (tmpfs) + 1,5 GB (kernel memory) = 3 GB
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Diffstat (limited to 'kexec/arch')
| -rw-r--r-- | kexec/arch/s390/kexec-image.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kexec/arch/s390/kexec-image.c b/kexec/arch/s390/kexec-image.c index be1e0f8..0c8937b 100644 --- a/kexec/arch/s390/kexec-image.c +++ b/kexec/arch/s390/kexec-image.c @@ -101,7 +101,7 @@ image_s390_load(int argc, char **argv, const char *kernel_buf, * we load the ramdisk directly behind the image with 1 MiB alignment. */ if (ramdisk) { - rd_buffer = slurp_file(ramdisk, &ramdisk_len); + rd_buffer = slurp_file_mmap(ramdisk, &ramdisk_len); if (rd_buffer == NULL) { fprintf(stderr, "Could not read ramdisk.\n"); return -1; |