Date: Sun, 20 Apr 2003 08:30:57 -0700 From: "Lucky Green" <shamrock@cypherpunks.to> To: <freebsd-current@freebsd.org> Subject: RE: Broken memory management on system with no swap Message-ID: <003201c30751$dccffef0$6601a8c0@VAIO650> In-Reply-To: <20030420101401.GA2821@HAL9000.homeunix.com>
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David wrote quoting Bruce: > > So the bug is mainly in vm making only a relatively useless > statistic > > available. On my systems, `Inact' is usually mainly for > (non-dirty) > > VMIO pages. > > Right. dillon was planning to separate out the dirty and > clean pages in the inactive queue at some point. ISTR that > his intent was along the lines of optimizing write clustering > by making dirty pages easier to find, or something along > those lines. But the number of inactive dirty pages is > useful as a statistic by itself, too. So how do I find out what is consuming those "inactive" pages? And how do I determine if those pages can be discarded or not? > > The system has little difficulty discarding these, so > > I haven't had problems with processes being killed despite > not using > > (much | any) swap since memories became cheap enough a few > years ago. > > I generally configure swap and use it only once in a blue > moon. Since there's no truly graceful way to handle an > out-of-swap condition, I'm usually glad that it's there once > in a while. But Lucky's concern is that confidential data > should never hit the disk. Exactly. Which is why I just replaced my old 128MB RAM/256MB swap server with a new 1GB RAM server. I still fail to understand why a setup that never was anywhere near running out of memory in the previous configuration would run out of memory with more RAM than it had RAM and swap combined. If I can't do in 1GB what I could do in 128 + 256 MB, then somewhere there is a bug. How do I find out where? It is correct that I don't want confidential data to hit the disk. I could use GBDE to encrypt the swap partition, but being one of the more active beta testers of GBDE, I am not convinced that GBDE is sufficiently well-tested at this time that I would want to rely on it for swap. Nor should I have to use GBDE to encrypt swap. That's why I bought a server with a GB of RAM. What am I missing? BTW, I since ran additional tests. Even with no GBDE device attached, the inactive memory eventually accounts for most of the memory shown by top: Mem: 30M Active, 788M Inact, 148M Wired, 34M Cache, 112M Buf, 1660K Free Swap: 2048M Total, 2048M Free (I did enable swap until somebody tells me how to determine what is causing the problem). Thanks, --Lucky
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