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author | ru <ru@FreeBSD.org> | 2002-08-13 14:37:41 +0000 |
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committer | ru <ru@FreeBSD.org> | 2002-08-13 14:37:41 +0000 |
commit | 6c13f40e3d6911a12b02e04b5637be3573065387 (patch) | |
tree | 5b69945b16137df9f34c6269710c094bc8f5eb73 /share/man/man7 | |
parent | 134d20225b799035cd28a9ab20f66f0007f690e6 (diff) | |
download | FreeBSD-src-6c13f40e3d6911a12b02e04b5637be3573065387.zip FreeBSD-src-6c13f40e3d6911a12b02e04b5637be3573065387.tar.gz |
mdoc(7) police: Bump document date, removed (again) hard sentence breaks..
Diffstat (limited to 'share/man/man7')
-rw-r--r-- | share/man/man7/tuning.7 | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/share/man/man7/tuning.7 b/share/man/man7/tuning.7 index cf110ea..daa93d3 100644 --- a/share/man/man7/tuning.7 +++ b/share/man/man7/tuning.7 @@ -4,7 +4,7 @@ .\" .\" $FreeBSD$ .\" -.Dd May 25, 2001 +.Dd June 25, 2002 .Dt TUNING 7 .Os .Sh NAME @@ -416,21 +416,28 @@ wasted memory but you should experiment to find out. .Pp The .Va vfs.write_behind -sysctl defaults to 1 (on). This tells the filesystem to issue media +sysctl defaults to 1 (on). +This tells the filesystem to issue media writes as full clusters are collected, which typically occurs when writing -large sequential files. The idea is to avoid saturating the buffer -cache with dirty buffers when it would not benefit I/O performance. However, +large sequential files. +The idea is to avoid saturating the buffer +cache with dirty buffers when it would not benefit I/O performance. +However, this may stall processes and under certain circumstances you may wish to turn it off. .Pp The .Va vfs.hirunningspace sysctl determines how much outstanding write I/O may be queued to -disk controllers system wide at any given instance. The default is +disk controllers system-wide at any given instance. +The default is usually sufficient but on machines with lots of disks you may want to bump -it up to four or five megabytes. Note that setting too high a value +it up to four or five megabytes. +Note that setting too high a value (exceeding the buffer cache's write threshold) can lead to extremely -bad clustering performance. Do not set this value arbitrarily high! Also, +bad clustering performance. +Do not set this value arbitrarily high! +Also, higher write queueing values may add latency to reads occuring at the same time. .Pp |