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On Sun, 2011-01-16 at 14:41 -0800, Grant wrote: |
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> >> I've been running without swap for quite a while, but my system goes |
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> >> into a near freeze whenever I undertake a large emerge such as |
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> >> chromium or openoffice. Is there anything I can do to prevent this |
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> >> besides turning swap back on? I have 3GB RAM and MAKEOPTS="-j1". |
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> >> |
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> >> - Grant |
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> >> |
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> >> |
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> > |
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> > As Volker says, don't turn swap off. Make it small if you must, but |
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> > keep some around. It's just disk space. |
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> |
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> I thought swap was no longer necessary on a machine with sufficient |
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> memory. I guess I took I some bad advice a while back. |
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The answer is that you have insufficient memory when emerging - hence |
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swap is necessary - turn it on! ionice will help, but it is alleviating |
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symptoms of lack of swap, not curing it. Downside in this case is |
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slower emerges and some will still be flaky. |
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You can use a temporary swapfile or swap over ndb for those special |
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cases if you have no swap partition. Also check the tunable |
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parameter /proc/sys/vm/swappiness to force memory to swap, or to get the |
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kernel to be very reluctant to use swap - can give the benefits of no |
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swap, but still have a safety margin with a small penalty when running |
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low on memory. google for "/proc/sys/vm/swappiness" |
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In short, swap is good, downside to swap is sometimes small pauses while |
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pages are swapped back in. But not having swap forces the kernel to |
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have a large overhead in trying to manage a low memory situation when it |
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gets low such as during an emerge. No swap is ok if you have a system |
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doing almost nothing, but with almost any normal use, 3G and no swap is |
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going to be trouble at times. |
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BillK |
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