The 'overloads-avoided' counter itself was removed several years ago by
commit 78c210e (Revert "knfsd: avoid overloading the CPU scheduler with
enormous load averages").
Signed-off-by: Scott Mayhew <[email protected]>
---
Documentation/filesystems/nfs/knfsd-stats.txt | 44 +++------------------------
1 file changed, 4 insertions(+), 40 deletions(-)
diff --git a/Documentation/filesystems/nfs/knfsd-stats.txt b/Documentation/filesystems/nfs/knfsd-stats.txt
index 64ced51..1a5d821 100644
--- a/Documentation/filesystems/nfs/knfsd-stats.txt
+++ b/Documentation/filesystems/nfs/knfsd-stats.txt
@@ -68,16 +68,10 @@ sockets-enqueued
rate of change for this counter is zero; significantly non-zero
values may indicate a performance limitation.
- This can happen either because there are too few nfsd threads in the
- thread pool for the NFS workload (the workload is thread-limited),
- or because the NFS workload needs more CPU time than is available in
- the thread pool (the workload is CPU-limited). In the former case,
- configuring more nfsd threads will probably improve the performance
- of the NFS workload. In the latter case, the sunrpc server layer is
- already choosing not to wake idle nfsd threads because there are too
- many nfsd threads which want to run but cannot, so configuring more
- nfsd threads will make no difference whatsoever. The overloads-avoided
- statistic (see below) can be used to distinguish these cases.
+ This can happen because there are too few nfsd threads in the thread
+ pool for the NFS workload (the workload is thread-limited), in which
+ case configuring more nfsd threads will probably improve the
+ performance of the NFS workload.
threads-woken
Counts how many times an idle nfsd thread is woken to try to
@@ -88,36 +82,6 @@ threads-woken
thing. The ideal rate of change for this counter will be close
to but less than the rate of change of the packets-arrived counter.
-overloads-avoided
- Counts how many times the sunrpc server layer chose not to wake an
- nfsd thread, despite the presence of idle nfsd threads, because
- too many nfsd threads had been recently woken but could not get
- enough CPU time to actually run.
-
- This statistic counts a circumstance where the sunrpc layer
- heuristically avoids overloading the CPU scheduler with too many
- runnable nfsd threads. The ideal rate of change for this counter
- is zero. Significant non-zero values indicate that the workload
- is CPU limited. Usually this is associated with heavy CPU usage
- on all the CPUs in the nfsd thread pool.
-
- If a sustained large overloads-avoided rate is detected on a pool,
- the top(1) utility should be used to check for the following
- pattern of CPU usage on all the CPUs associated with the given
- nfsd thread pool.
-
- - %us ~= 0 (as you're *NOT* running applications on your NFS server)
-
- - %wa ~= 0
-
- - %id ~= 0
-
- - %sy + %hi + %si ~= 100
-
- If this pattern is seen, configuring more nfsd threads will *not*
- improve the performance of the workload. If this patten is not
- seen, then something more subtle is wrong.
-
threads-timedout
Counts how many times an nfsd thread triggered an idle timeout,
i.e. was not woken to handle any incoming network packets for
--
1.9.3
On Wed, Apr 29, 2015 at 10:38:26AM -0400, Scott Mayhew wrote:
> The 'overloads-avoided' counter itself was removed several years ago by
> commit 78c210e (Revert "knfsd: avoid overloading the CPU scheduler with
> enormous load averages").
Thanks for cleaning this up.--b.
>
> Signed-off-by: Scott Mayhew <[email protected]>
> ---
> Documentation/filesystems/nfs/knfsd-stats.txt | 44 +++------------------------
> 1 file changed, 4 insertions(+), 40 deletions(-)
>
> diff --git a/Documentation/filesystems/nfs/knfsd-stats.txt b/Documentation/filesystems/nfs/knfsd-stats.txt
> index 64ced51..1a5d821 100644
> --- a/Documentation/filesystems/nfs/knfsd-stats.txt
> +++ b/Documentation/filesystems/nfs/knfsd-stats.txt
> @@ -68,16 +68,10 @@ sockets-enqueued
> rate of change for this counter is zero; significantly non-zero
> values may indicate a performance limitation.
>
> - This can happen either because there are too few nfsd threads in the
> - thread pool for the NFS workload (the workload is thread-limited),
> - or because the NFS workload needs more CPU time than is available in
> - the thread pool (the workload is CPU-limited). In the former case,
> - configuring more nfsd threads will probably improve the performance
> - of the NFS workload. In the latter case, the sunrpc server layer is
> - already choosing not to wake idle nfsd threads because there are too
> - many nfsd threads which want to run but cannot, so configuring more
> - nfsd threads will make no difference whatsoever. The overloads-avoided
> - statistic (see below) can be used to distinguish these cases.
> + This can happen because there are too few nfsd threads in the thread
> + pool for the NFS workload (the workload is thread-limited), in which
> + case configuring more nfsd threads will probably improve the
> + performance of the NFS workload.
>
> threads-woken
> Counts how many times an idle nfsd thread is woken to try to
> @@ -88,36 +82,6 @@ threads-woken
> thing. The ideal rate of change for this counter will be close
> to but less than the rate of change of the packets-arrived counter.
>
> -overloads-avoided
> - Counts how many times the sunrpc server layer chose not to wake an
> - nfsd thread, despite the presence of idle nfsd threads, because
> - too many nfsd threads had been recently woken but could not get
> - enough CPU time to actually run.
> -
> - This statistic counts a circumstance where the sunrpc layer
> - heuristically avoids overloading the CPU scheduler with too many
> - runnable nfsd threads. The ideal rate of change for this counter
> - is zero. Significant non-zero values indicate that the workload
> - is CPU limited. Usually this is associated with heavy CPU usage
> - on all the CPUs in the nfsd thread pool.
> -
> - If a sustained large overloads-avoided rate is detected on a pool,
> - the top(1) utility should be used to check for the following
> - pattern of CPU usage on all the CPUs associated with the given
> - nfsd thread pool.
> -
> - - %us ~= 0 (as you're *NOT* running applications on your NFS server)
> -
> - - %wa ~= 0
> -
> - - %id ~= 0
> -
> - - %sy + %hi + %si ~= 100
> -
> - If this pattern is seen, configuring more nfsd threads will *not*
> - improve the performance of the workload. If this patten is not
> - seen, then something more subtle is wrong.
> -
> threads-timedout
> Counts how many times an nfsd thread triggered an idle timeout,
> i.e. was not woken to handle any incoming network packets for
> --
> 1.9.3