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SUNRPC: Move congestion window constants to header file 

I would like to use one of the RPC client's congestion algorithm
constants in transport-specific code.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2014-05-28 10:34:49 -04:00 committed by Anna Schumaker
parent 18906972aa
commit 4f4cf5ad6f
2 changed files with 15 additions and 19 deletions
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6
include/linux/sunrpc/xprt.h
View File

@ -24,6 +24,12 @@
#define RPC_MAX_SLOT_TABLE_LIMIT (65536U)
#define RPC_MAX_SLOT_TABLE RPC_MAX_SLOT_TABLE_LIMIT
#define RPC_CWNDSHIFT (8U)
#define RPC_CWNDSCALE (1U << RPC_CWNDSHIFT)
#define RPC_INITCWND RPC_CWNDSCALE
#define RPC_MAXCWND(xprt) ((xprt)->max_reqs << RPC_CWNDSHIFT)
#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
/*
* This describes a timeout strategy
*/

28
net/sunrpc/xprt.c
View File

@ -71,24 +71,6 @@ static void xprt_destroy(struct rpc_xprt *xprt);
static DEFINE_SPINLOCK(xprt_list_lock);
static LIST_HEAD(xprt_list);
/*
* The transport code maintains an estimate on the maximum number of out-
* standing RPC requests, using a smoothed version of the congestion
* avoidance implemented in 44BSD. This is basically the Van Jacobson
* congestion algorithm: If a retransmit occurs, the congestion window is
* halved; otherwise, it is incremented by 1/cwnd when
*
* - a reply is received and
* - a full number of requests are outstanding and
* - the congestion window hasn't been updated recently.
*/
#define RPC_CWNDSHIFT (8U)
#define RPC_CWNDSCALE (1U << RPC_CWNDSHIFT)
#define RPC_INITCWND RPC_CWNDSCALE
#define RPC_MAXCWND(xprt) ((xprt)->max_reqs << RPC_CWNDSHIFT)
#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
/**
* xprt_register_transport - register a transport implementation
* @transport: transport to register
@ -446,7 +428,15 @@ EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
* @task: recently completed RPC request used to adjust window
* @result: result code of completed RPC request
*
* We use a time-smoothed congestion estimator to avoid heavy oscillation.
* The transport code maintains an estimate on the maximum number of out-
* standing RPC requests, using a smoothed version of the congestion
* avoidance implemented in 44BSD. This is basically the Van Jacobson
* congestion algorithm: If a retransmit occurs, the congestion window is
* halved; otherwise, it is incremented by 1/cwnd when
*
* - a reply is received and
* - a full number of requests are outstanding and
* - the congestion window hasn't been updated recently.
*/
void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
{