| Message ID | 1430318306-26029-1-git-send-email-smayhew@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <smayhew@redhat.com> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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
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 <smayhew@redhat.com> --- Documentation/filesystems/nfs/knfsd-stats.txt | 44 +++------------------------ 1 file changed, 4 insertions(+), 40 deletions(-)