Have you tested that this does what you want? If it does, I think
we'll want to implement this so that we actually release the memory,
but continue accounting it.
On Thu, Sep 27, 2012 at 2:56 PM, Jim Schutt <jaschut@xxxxxxxxxx> wrote:
> Under a sustained cephfs write load where the offered load is higher
> than the storage cluster write throughput, a backlog of replication ops
> that arrive via the cluster messenger builds up. The client message
> policy throttler, which should be limiting the total write workload
> accepted by the storage cluster, is unable to prevent it, for any
> value of osd_client_message_size_cap, under such an overload condition.
>
> The root cause is that op data is released too early, in op_applied().
>
> If instead the op data is released at op deletion, then the limit
> imposed by the client policy throttler applies over the entire
> lifetime of the op, including commits of replication ops. That
> makes the policy throttler an effective means for an OSD to
> protect itself from a sustained high offered load, because it can
> effectively limit the total, cluster-wide resources needed to process
> in-progress write ops.
>
> Signed-off-by: Jim Schutt <jaschut@xxxxxxxxxx>
> ---
> src/osd/ReplicatedPG.cc | 4 ----
> 1 files changed, 0 insertions(+), 4 deletions(-)
>
> diff --git a/src/osd/ReplicatedPG.cc b/src/osd/ReplicatedPG.cc
> index a64abda..80bec2a 100644
> --- a/src/osd/ReplicatedPG.cc
> +++ b/src/osd/ReplicatedPG.cc
> @@ -3490,10 +3490,6 @@ void ReplicatedPG::op_applied(RepGather *repop)
> dout(10) << "op_applied " << *repop << dendl;
> if (repop->ctx->op)
> repop->ctx->op->mark_event("op_applied");
> -
> - // discard my reference to the buffer
> - if (repop->ctx->op)
> - repop->ctx->op->request->clear_data();
>
> repop->applying = false;
> repop->applied = true;
> --
> 1.7.8.2
>
>
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