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Date:      Sun, 03 Feb 2002 09:19:46 -0500
From:      Sam <sam@wa4phy.net>
To:        freebsd-questions@freebsd.org
Cc:        freebsd-stable@freebsd.org
Subject:   Normal behavior?
Message-ID:  <3C5D4702.661789BA@vortex.wa4phy.net>

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I'd appreciate some clarification about the behavior of the softupdates
as it relates to disk writes.  Situation:  Have noticed that during an
ftp session with relatively high (150 Kbs) data stream, I notice after
what appears to be a short burst, i.e., 130 packets (viewed with systat
-vm) there is a considerable delay before the next batch.  Graphicaly
viewing thruput with xsysinfo, I watch the disk write for each "batch",
but while the write is happening, there appears to be a significant
delay before the next packet stream is graphicaly displayed.  Is this a
function of softupdates, combined with the fact that the ATA drive has
to be serviced by the processor, and the switcher can't service two
things at once, or what.  How often does the data that needs to be
written actually get written to the disk, or do I misunderstand how
softupdates works?  Essentially, what it appears to me that is
happening, is the packet stream is "suspended" while the disk is being
written to.  Is that a correct assumption?  Since softupdates is on by
default now, what damage would I do if I turned it off?  Is that to my
best interest?

Thanks..

Sam

--
Just because you're moving fast         |       BURMA SHAVE
doesn't mean that you're really         |
going anwhere at all!                   |




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