Messages in this thread | | | Date | Fri, 14 May 1999 18:22:13 +0200 (CEST) | From | Andrea Arcangeli <> | Subject | Re: All the problems with 2.2.8/2.3.x and bdflush/update |
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On Fri, 14 May 1999, Zack Weinberg wrote:
>You get an additional process slot, which is not to be sneezed at. >More significant, though, you have a guarantee that data is flushed >back within some short period of time, no matter what state the system
You don't care to run update always with the same delta-time between different runs. update does "sync some old buffer to disk". If you'll delay the call of sync_old_buffers() then as worse the next time you'll sync to disk some more dirty buffer.
The stability of the VM system is enforced by bdflush/kswapd and not from uptime.
>is in. You don't seem to think this is important, but to anyone who >maintains a server with key data on it, it is *critical*.
If you need filesystem integrity after a crash (or better after a power fail... ;), then you need a fault toulerant fs and not ext2. update can't save you, it can only alleviate the damage.
>I also think that with update rolled into bdflush, it will be possible >to do the job faster and with less bottlenecking. See below.
You sometime force mark_dirty_buffers() to wait all dirty buffers to be flushed away before allowing it to go ahead.
>block; instead you call flush_dirty_buffers directly. I'm not sure >that's a good idea; can you justify it?
Think if bdflush was writing the last bdflush_param.ndirty buffer. You'll issue a sleep_on() but you'll get a wakeup without waiting that some more buffer is been synced back to disk. And my way will avoid many task switch ping-pong.
>where `2.2.8+p' is 2.2.8 plus the patch at the end of this message.
Please let me see the numbers of 2.2.8_andrea1.bz2 doing the same on the same heardware, I would be interested.
Andrea Arcangeli
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