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On Wed, May 25, 2011 at 11:58 AM, Volker Armin Hemmann |
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<volkerarmin@××××××××××.com> wrote: |
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> On Wednesday 25 May 2011 10:31:19 Paul Hartman wrote: |
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> |
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>> When I move the swap to a slow SD card instead (2MB/sec transfer |
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>> rate), even in that slow device, swapoff on the eMMC swap partition |
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>> with ~500M in-use takes about 2 or 3 minutes at most with the data |
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>> being swapped slowly into the SD card. |
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>> |
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>> So I think in your case it should be much faster than that! |
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> |
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> you are comparing apples with oranges (harddisks with moving arms with solid |
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> state devices). |
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> |
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> Do yourself a favour. Look up how long a harddisk needs to position its head. |
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Yeah, measuring speed in microseconds versus milliseconds. :) |
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My SD read/write speed is about 0.9MB/sec in benchmark, and about 2 |
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MB/sec in real-life swap usage. Based on Alex's timings it seems his |
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HDD is getting about 0.5 MB/sec in swap usage. HDD benchmark random |
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read/write is usually faster than that. But probably you're right and |
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the seek operations are really killing it. HDD is about 20 times |
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slower than SD card in seeking. |
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If he has a USB flash drive, or memory card reader, he can use it for |
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swap and see if it's any better or worse. I am curious how it will |
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compare. |
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Or, if he has multiple disks, he could create more swap partitions |
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with equal priority and kernel will stripe/load balance automatically, |
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hopefully improving his swap performance. |
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Or better yet, figure out why his system is swapping at all which is |
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what he was going for I think. With 8 GB I think he should be able to |
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disable swap entirely anyway. :) |
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