Commit-ID: 5cc6517abdeccb6690b344a43b5ce8eaee82da3c Gitweb: http://git.kernel.org/tip/5cc6517abdeccb6690b344a43b5ce8eaee82da3c Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Fri, 13 Aug 2010 16:34:22 -0700 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Fri, 20 Aug 2010 09:00:14 -0700 rcu: document ways of stalling updates in low-memory situations Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> --- Documentation/RCU/checklist.txt | 23 ++++++++++++++++------- 1 files changed, 16 insertions(+), 7 deletions(-) diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index c7c6788..0c134f8 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -218,13 +218,22 @@ over a rather long period of time, but improvements are always welcome! include: a. Keeping a count of the number of data-structure elements - used by the RCU-protected data structure, including those - waiting for a grace period to elapse. Enforce a limit - on this number, stalling updates as needed to allow - previously deferred frees to complete. - - Alternatively, limit only the number awaiting deferred - free rather than the total number of elements. + used by the RCU-protected data structure, including + those waiting for a grace period to elapse. Enforce a + limit on this number, stalling updates as needed to allow + previously deferred frees to complete. Alternatively, + limit only the number awaiting deferred free rather than + the total number of elements. + + One way to stall the updates is to acquire the update-side + mutex. (Don't try this with a spinlock -- other CPUs + spinning on the lock could prevent the grace period + from ever ending.) Another way to stall the updates + is for the updates to use a wrapper function around + the memory allocator, so that this wrapper function + simulates OOM when there is too much memory awaiting an + RCU grace period. There are of course many other + variations on this theme. b. Limiting update rate. For example, if updates occur only once per hour, then no explicit rate limiting is required, -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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