Quoting Sukadev Bhattiprolu (sukadev@xxxxxxxxxxxxxxxxxx):
>
> Oren,
>
> I see that patch 3/6 (deny external checkpoint unless frozen) in this
> set was merged in v14, but do you have any plans/objections to merging
> this optimization patch ? Serge had acked an earlier version of this
> patch.
>
> Suka
>
> Sukadev Bhattiprolu [sukadev@xxxxxxxxxxxxxxxxxx] wrote:
> |
> | From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> | Date: Thu, 12 Mar 2009 14:19:54 -0700
> | Subject: [PATCH 3/6] Check 'may_checkpoint()' early
> |
> | We currently check if a task is checkpointable when writing the task
> | information to checkpoint file. The small downside of doing this check
> | late is that we may have processed several processes in the tree before
> | hitting one that cannot be checkpointed.
> |
> | We anyway walk the process tree we are checkpointing earlier, while
> | counting the tasks. We could check if all processes in the tree are
> | checkpointable at that time and fail early if any of them are not.
> | Since the process tree should be frozen, checking earlier should not
> | matter ?
> |
> | For now, the patch leaves the existing check in cr_write_pids(). We
> | can remove that later.
> |
> | Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> | ---
> | checkpoint/checkpoint.c | 9 +++++++++
> | 1 files changed, 9 insertions(+), 0 deletions(-)
> |
> | diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
> | index ed4fd3d..dae9b97 100644
> | --- a/checkpoint/checkpoint.c
> | +++ b/checkpoint/checkpoint.c
> | @@ -341,11 +341,18 @@ static int cr_tree_count_tasks(struct cr_ctx *ctx)
> | struct task_struct **tasks_arr = ctx->tasks_arr;
> | int tasks_nr = ctx->tasks_nr;
> | int nr = 0;
> | + int ret;
> |
> | read_lock(&tasklist_lock);
> |
> | /* count tasks via DFS scan of the tree */
> | while (1) {
> | + ret = cr_may_checkpoint_task(task, ctx);
> | + if (ret < 0) {
> | + nr = ret;
> | + break;
> | + }
> | +
> | if (tasks_arr) {
> | /* unlikely, but ... */
> | if (nr == tasks_nr)
> | @@ -401,6 +408,8 @@ static int cr_build_tree(struct cr_ctx *ctx)
> |
> | /* count tasks (no side effects) */
> | n = cr_tree_count_tasks(ctx);
> | + if (n < 0)
> | + return n;
This hunk is already in v14.
-serge
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