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| author | Dipankar Sarma <dipankar@in.ibm.com> | 2004-08-22 22:57:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2004-08-22 22:57:42 -0700 |
| commit | daf86b08a178f950c0e0ec073c25cc392dbbc789 (patch) | |
| tree | 8b76bd66d2b2c426d42282633c6525716ea9bad6 /include | |
| parent | f0f4d6e41008746f51db2c795469e1707e516672 (diff) | |
| download | history-daf86b08a178f950c0e0ec073c25cc392dbbc789.tar.gz | |
[PATCH] RCU: low latency rcu
This patch makes RCU callbacks friendly to scheduler. It helps low latency
by limiting the number of callbacks invoked per tasklet handler. Since we
cannot schedule during a single softirq handler, this reduces size of
non-preemptible section significantly, specially under heavy RCU updates.
The limiting is done through a kernel parameter rcupdate.maxbatch which is
the maximum number of RCU callbacks to invoke during a single tasklet
handler.
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/rcupdate.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 226ce765c031ae..b689ab6108bdb9 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -99,6 +99,8 @@ struct rcu_data { struct rcu_head **nxttail; struct rcu_head *curlist; struct rcu_head **curtail; + struct rcu_head *donelist; + struct rcu_head **donetail; }; DECLARE_PER_CPU(struct rcu_data, rcu_data); @@ -113,6 +115,8 @@ extern struct rcu_ctrlblk rcu_ctrlblk; #define RCU_curlist(cpu) (per_cpu(rcu_data, (cpu)).curlist) #define RCU_nxttail(cpu) (per_cpu(rcu_data, (cpu)).nxttail) #define RCU_curtail(cpu) (per_cpu(rcu_data, (cpu)).curtail) +#define RCU_donelist(cpu) (per_cpu(rcu_data, (cpu)).donelist) +#define RCU_donetail(cpu) (per_cpu(rcu_data, (cpu)).donetail) static inline int rcu_pending(int cpu) { @@ -127,6 +131,9 @@ static inline int rcu_pending(int cpu) if (!RCU_curlist(cpu) && RCU_nxtlist(cpu)) return 1; + if (RCU_donelist(cpu)) + return 1; + /* The rcu core waits for a quiescent state from the cpu */ if (RCU_quiescbatch(cpu) != rcu_ctrlblk.cur || RCU_qs_pending(cpu)) return 1; |