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375$415eb37d@crater_reader.dragonflybsd.org>
From: Matthew Dillon <dillon@apollo.backplane.com>
Subject: Re: Machine unresponsive with cache_lock: blocked on... message
Date: Sat, 20 Mar 2010 13:46:22 -0700 (PDT)
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:Hm, I understand if hammer cleanup removes other data from cache, but
:why should the disk cache usage push out data to swap?
:I just tried a hammer cleanup on a completely idle system with 1.5G
:memory in single user mode, and during the reblocking it started to
:use swap and became unresponsive - is this really working as expected?
:
:Cheers,
:Johannes

    You couldn't ^C the reblock?  Reblocking works the storage system
    pretty heavily, performance issues are not necessarily going to be
    related to paging activity.  Anything which has to read from disk will
    be slow.

    How does the system know what pages are idle and what pages are not
    idle when the whole system is idle?  How can the system distinguish
    between the one-time scan that the reblocker does verses, say, someone
    rdist'ing a dataset which would easily fit in memory that we DO want
    to cache?

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>