Messages in this thread | | | From | Denis Vlasenko <> | Subject | Re: Raid 0 Swap? | Date | Mon, 18 Sep 2006 11:50:22 +0200 |
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On Monday 04 September 2006 12:46, Jan Engelhardt wrote: > >> I thought kernel data weren't swapped at all? > > If the swap code was swapped, who would swap it in again? > > >Well, it's not that simple. Kernel uses both swappable and > >non-swappable memory internally. For some things, it's > >unswappable, for some, it's swappable. In general, it's > >impossible to say which parts of kernel will break (and > >in wich ways) if swap goes havoc. > > In general, everything you type in as C code (.bss, .data, .text) should be > unswappable. kmalloc()ed areas are resident too, and kmalloc has a > parameter which defines whether the allocation can/cannot push userspace > pages into the swap (GFP_ATOMIC/GFP_IO). So if there is some > kernel-allocation swapped out, it is most likely to be marked as > 'userspace' so that the same algorithms can be used for swapin and -out.
What are you guys talking about? IIRC kernel doesn't use swap for its vital data structures. I recall only one kernel thing which goes into swap: tmpfs data. Caching network filesystems may also use swappable data, but currently grep catches only cifs.
IOW swap is for dirtied userspace data. Please correct me if I am wrong here. -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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