Messages in this thread | | | Date | Thu, 23 Jun 2011 14:51:47 +0800 | From | Cong Wang <> | Subject | Re: [PATCH v2 2/4] mm: make the threshold of enabling THP configurable |
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于 2011年06月22日 22:40, Andrea Arcangeli 写道: > On Wed, Jun 22, 2011 at 07:07:25PM +0800, Cong Wang wrote: >> Actually, if we move this out of kernel, to user-space, everything >> you worried will be solved by just changing the user-space code. >> Just add the following pseudo code into your init script, >> >> if [ $total_memory -lt 512 ] >> then >> echo never> /sys/kernel/mm/transparent_hugepage/enabled >> fi > > By the time this script runs some app may have allocated hugepages > already potentially wasting mbytes of ram and undoing the > min_free_kbytes isn't possible from userland using the kernel > algorithm (it is possible actually but it's not nearly as simple as > the above).
I remember there is a way to tell init-scripts to run it as early as possible. :)
> > There's no reason to complicate things and involve userland here when > a simple kernel check can get the default right without userland > dependency. Plus if this user really wants THP on 512m of ram he can > still enable it and run hugeadm to enable antifrag too, without the > need of =force. And forcing when PSE is enabled sounds impossible to be > useful (maybe with the except of nopentium being passed to the kernel ;). > > There is no bug here, just send that printk cleanup and if you really > want to save 8k the patch to change the number of hash heads structs > at boot, like for dcache/icache. No other change required.
I never said this is a bug, I just don't think it is flexible. ;)
> > After you do the above, you can go ahead picking one kernel crashing > bug and fix it, that is more useful than making this 512m thing a > .config variable or anything like that, .config is a nightmare already > so it's probably better not to add anything there.
Well, I can't agree with this point.
Since we can't persuade each other, I give up.
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