diff options
Diffstat (limited to 'compiler/main/GhcMake.hs')
| -rw-r--r-- | compiler/main/GhcMake.hs | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/compiler/main/GhcMake.hs b/compiler/main/GhcMake.hs index bb1c8e3f2d..9197b2c1f6 100644 --- a/compiler/main/GhcMake.hs +++ b/compiler/main/GhcMake.hs @@ -762,7 +762,12 @@ parUpsweep n_jobs old_hpt stable_mods cleanup sccs = do let updNumCapabilities = liftIO $ do n_capabilities <- getNumCapabilities - unless (n_capabilities /= 1) $ setNumCapabilities n_jobs + n_cpus <- getNumProcessors + -- Setting number of capabilities more than + -- CPU count usually leads to high userspace + -- lock contention. Trac #9221 + let n_caps = min n_jobs n_cpus + unless (n_capabilities /= 1) $ setNumCapabilities n_caps return n_capabilities -- Reset the number of capabilities once the upsweep ends. let resetNumCapabilities orig_n = liftIO $ setNumCapabilities orig_n |