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Linux-2.4.1-pre11 / ll_rw_b watermark metric?

DISCUSSION Petr Vandrovec 2 participants 2 messages Jan 29, 2001

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Quoted 7 lines · Dieter Nützel

I have pre11 running with Andrea's suggested fix.

        high_queued_sectors = total_ram / 3;
        low_queued_sectors = high_queued_sectors / 2;
        if (low_queued_sectors < 0)
                low_queued_sectors = total_ram / 2;

I have one question: How it can happen that low_queued_sectors is less than zero with this changed logic? (And if it get triggered, low_queued_sectors will be greater than high_queued_sectors - which is not what we want...)

But it is certainly better than 2.4.0-pre8 approach, as with 200MB of memory (exactly 192MB left unused) you can end up with low_queued_sectors == 0... And it does not give you optimal behavior.
Best regards,
Petr Vandrovec [email protected]

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#1 lore raw
Quoted 9 lines · Petr Vandrovec
Quoted 7 lines · Dieter Nützel

I have pre11 running with Andrea's suggested fix.

        high_queued_sectors = total_ram / 3;
        low_queued_sectors = high_queued_sectors / 2;
        if (low_queued_sectors < 0)
                low_queued_sectors = total_ram / 2;
Quoted 4 lines

I have one question: How it can happen that low_queued_sectors is less than zero with this changed logic? (And if it get triggered, low_queued_sectors will be greater than high_queued_sectors - which is not what we want...)

This wasn't my change, but you're right it's wrong.

Quoted 3 lines

But it is certainly better than 2.4.0-pre8 approach, as with 200MB of memory (exactly 192MB left unused) you can end up with low_queued_sectors == 0... And it does not give you optimal behavior.

Same here, definitely not right either. Dunno how I missed that.

Signature · 6 lines
Jens Axboe

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