Re: [PATCH v2 5/6] mm: Support address range reclaim

Namhyung Kim
2013-04-24T11:01:51Z

Hi Minchan,

On Wed, 24 Apr 2013 10:41:03 +0900, Minchan Kim wrote:
> This patch adds address range reclaim of a process.
> The requirement is following as,
>
> Like webkit1, it uses a address space for handling multi tabs.
> IOW, it uses *one* process model so all tabs shares address space
> of the process. In such scenario, per-process reclaim is rather
> coarse-grained so this patch supports more fine-grained reclaim
> for being able to reclaim target address range of the process.
> For reclaim target range, you should use following format.
>
> echo [addr] [size-byte] > /proc/pid/reclaim
>
> addr should be page-aligned.
>
> So now reclaim konb's interface is following as.
>
> echo file > /proc/pid/reclaim
> reclaim file-backed pages only
>
> echo anon > /proc/pid/reclaim
> reclaim anonymous pages only
>
> echo all > /proc/pid/reclaim
> reclaim all pages
>
> echo $((1<<20)) 8192 > /proc/pid/reclaim
> reclaim pages in (0x100000 - 0x102000)
>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> fs/proc/task_mmu.c | 88 ++++++++++++++++++++++++++++++++++++++++++++----------
> mm/internal.h | 3 ++
> 2 files changed, 76 insertions(+), 15 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 79b674e..dff9756 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -12,6 +12,7 @@
> #include <linux/swap.h>
> #include <linux/swapops.h>
> #include <linux/mm_inline.h>
> +#include <linux/ctype.h>
>
> #include <asm/elf.h>
> #include <asm/uaccess.h>
> @@ -1239,11 +1240,14 @@ static ssize_t reclaim_write(struct file *file, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> struct task_struct *task;
> - char buffer[PROC_NUMBUF];
> + char buffer[200];
> struct mm_struct *mm;
> struct vm_area_struct *vma;
> enum reclaim_type type;
> char *type_buf;
> + struct mm_walk reclaim_walk = {};
> + unsigned long start = 0;
> + unsigned long end = 0;
>
> memset(buffer, 0, sizeof(buffer));
> if (count > sizeof(buffer) - 1)
> @@ -1259,42 +1263,96 @@ static ssize_t reclaim_write(struct file *file, const char __user *buf,
> type = RECLAIM_ANON;
> else if (!strcmp(type_buf, "all"))
> type = RECLAIM_ALL;
> + else if (isdigit(*type_buf))
> + type = RECLAIM_RANGE;
> else
> - return -EINVAL;
> + goto out_err;
> +
> + if (type == RECLAIM_RANGE) {
> + int ret;
> + size_t len;
> + unsigned long len_in;
> + char *token;
> +
> + token = strsep(&type_buf, " ");
> + if (!token)
> + goto out_err;
> + ret = kstrtoul(token, 10, &start);

Why not using

start = memparse(token, NULL);

to support something like:

# echo 0x100000 8K > /proc/pid/reclaim

Thanks,
Namhyung