core: run many bricks within one glusterfsd process

This patch adds support for multiple brick translator stacks running in
a single brick server process.  This reduces our per-brick memory usage
by approximately 3x, and our appetite for TCP ports even more.  It also
creates potential to avoid process/thread thrashing, and to improve QoS
by scheduling more carefully across the bricks, but realizing that
potential will require further work.

Multiplexing is controlled by the "cluster.brick-multiplex" global
option.  By default it's off, and bricks are started in separate
processes as before.  If multiplexing is enabled, then *compatible*
bricks (mostly those with the same transport options) will be started in
the same process.

Backport of:
> Change-Id: I45059454e51d6f4cbb29a4953359c09a408695cb
> BUG: 1385758
> Reviewed-on: https://review.gluster.org/14763

Change-Id: I4bce9080f6c93d50171823298fdf920258317ee8
BUG: 1418091
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: https://review.gluster.org/16496
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/xlators/protocol/server/src/server-rpc-fops.c b/xlators/protocol/server/src/server-rpc-fops.c
index 0a5497f22e0..5bb40a77515 100644
--- a/xlators/protocol/server/src/server-rpc-fops.c
+++ b/xlators/protocol/server/src/server-rpc-fops.c
@@ -3385,10 +3385,8 @@ server_compound_resume (call_frame_t *frame, xlator_t *bound_xl)
         int                     length  = 0;
         int                     op_errno = ENOMEM;
         compound_req            *c_req  = NULL;
-        xlator_t                *this   = NULL;
 
         state = CALL_STATE (frame);
-        this = frame->this;
 
         if (state->resolve.op_ret != 0) {
                 ret = state->resolve.op_ret;
@@ -3422,8 +3420,7 @@ server_compound_resume (call_frame_t *frame, xlator_t *bound_xl)
         }
 
         STACK_WIND (frame, server_compound_cbk,
-                    FIRST_CHILD(this),
-                    FIRST_CHILD(this)->fops->compound,
+                    bound_xl, bound_xl->fops->compound,
                     args, state->xdata);
 
         return 0;