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  1. 07 Dec, 2006 1 commit
    • Eric Dumazet's avatar
      [PATCH] rcu: add a prefetch() in rcu_do_batch() · 1c69d921
      Eric Dumazet authored 
      
On some workloads, (for example when lot of close() syscalls are done), RCU
qlen can be quite large, and RCU heads are no longer in cpu cache when
rcu_do_batch() is called.

This patch adds a prefetch() in rcu_do_batch() to give CPU a hint to bring
back cache lines containing 'struct rcu_head's.

Most list manipulations macros include prefetch(), but not open coded ones
(at least with current C compilers :) )

I got a nice speedup on a trivial benchmark (3.48 us per iteration instead
of 3.95 us on a 1.6 GHz Pentium-M)

while (1) { pipe(p); close(fd[0]); close(fd[1]);}
Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      1c69d921
  3. 04 Oct, 2006 1 commit
    • Oleg Nesterov's avatar
      [PATCH] rcu: simplify/improve batch tuning · 20e9751b
      Oleg Nesterov authored 
      
Kill a hard-to-calculate 'rsinterval' boot parameter and per-cpu
rcu_data.last_rs_qlen.  Instead, it adds adds a flag rcu_ctrlblk.signaled,
which records the fact that one of CPUs has sent a resched IPI since the
last rcu_start_batch().

Roughly speaking, we need two rcu_start_batch()s in order to move callbacks
from ->nxtlist to ->donelist.  This means that when ->qlen exceeds qhimark
and continues to grow, we should send a resched IPI, and then do it again
after we gone through a quiescent state.

On the other hand, if it was already sent, we don't need to do it again
when another CPU detects overflow of the queue.
Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Acked-by: default avatarPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      20e9751b
  5. 13 Sep, 2006 1 commit
  7. 31 Jul, 2006 1 commit
  9. 03 Jul, 2006 1 commit
  11. 27 Jun, 2006 3 commits
  13. 23 Jun, 2006 1 commit
  15. 15 May, 2006 1 commit
  17. 26 Apr, 2006 2 commits
  19. 24 Mar, 2006 1 commit
  21. 23 Mar, 2006 2 commits
  23. 20 Mar, 2006 1 commit
  25. 08 Mar, 2006 1 commit
    • Dipankar Sarma's avatar
      [PATCH] rcu batch tuning · 21a1ea9e
      Dipankar Sarma authored 
      
This patch adds new tunables for RCU queue and finished batches.  There are
two types of controls - number of completed RCU updates invoked in a batch
(blimit) and monitoring for high rate of incoming RCUs on a cpu (qhimark,
qlowmark).

By default, the per-cpu batch limit is set to a small value.  If the input
RCU rate exceeds the high watermark, we do two things - force quiescent
state on all cpus and set the batch limit of the CPU to INTMAX.  Setting
batch limit to INTMAX forces all finished RCUs to be processed in one shot.
 If we have more than INTMAX RCUs queued up, then we have bigger problems
anyway.  Once the incoming queued RCUs fall below the low watermark, the
batch limit is set to the default.
Signed-off-by: default avatarDipankar Sarma <dipankar@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      21a1ea9e
  27. 10 Jan, 2006 2 commits
  29. 09 Jan, 2006 2 commits
  31. 08 Jan, 2006 3 commits
  33. 12 Dec, 2005 2 commits
    • Srivatsa Vaddagiri's avatar
      [PATCH] Fix RCU race in access of nohz_cpu_mask · c3f59023
      Srivatsa Vaddagiri authored 
      
Accessing nohz_cpu_mask before incrementing rcp->cur is racy.  It can cause
tickless idle CPUs to be included in rsp->cpumask, which will extend
graceperiods unnecessarily.

Fix this race.  It has been tested using extensions to RCU torture module
that forces various CPUs to become idle.
Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c3f59023
    • Dipankar Sarma's avatar
      [PATCH] add rcu_barrier() synchronization point · ab4720ec
      Dipankar Sarma authored 
      
This introduces a new interface - rcu_barrier() which waits until all
the RCUs queued until this call have been completed.

Reiser4 needs this, because we do more than just freeing memory object
in our RCU callback: we also remove it from the list hanging off
super-block.  This means, that before freeing reiser4-specific portion
of super-block (during umount) we have to wait until all pending RCU
callbacks are executed.

The only change of reiser4 made to the original patch, is exporting of
rcu_barrier().

Cc: Hans Reiser <reiser@namesys.com>
Cc: Vladimir V. Saveliev <vs@namesys.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      ab4720ec
  35. 30 Oct, 2005 1 commit
  37. 17 Oct, 2005 2 commits
    • Eric Dumazet's avatar
      [PATCH] rcu: keep rcu callback event counter · 5ee832db
      Eric Dumazet authored 
      
This makes call_rcu() keep track of how many events there are on the RCU
list, and cause a reschedule event when the list gets too long.

This helps keep RCU event lists down.
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      5ee832db
    • Linus Torvalds's avatar
      Increase default RCU batching sharply · 2cc78eb5
      Linus Torvalds authored 
      
Dipankar made RCU limit the batch size to improve latency, but that
approach is unworkable: it can cause the RCU queues to grow without
bounds, since the batch limiter ended up limiting the callbacks.

So make the limit much higher, and start planning on instead limiting
the batch size by doing RCU callbacks more often if the queue looks like
it might be growing too long.
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2cc78eb5
  39. 09 Sep, 2005 1 commit
  41. 01 May, 2005 2 commits
  43. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored 
      Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
      1da177e4