Messages in this thread | | | Date | Mon, 15 Nov 2010 15:07:57 +0900 | Subject | Re: fadvise DONTNEED implementation (or lack thereof) | From | Minchan Kim <> |
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On Sun, Nov 14, 2010 at 2:09 PM, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> On Tue, 9 Nov 2010 16:28:02 +0900 (JST), KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> > So, I don't think application developers will use fadvise() aggressively >> > because we don't have a cross platform agreement of a fadvice behavior. >> > >> I strongly disagree. For a long time I have been trying to resolve >> interactivity issues caused by my rsync-based backup script. Many kernel >> developers have said that there is nothing the kernel can do without >> more information from user-space (e.g. cgroups, madvise). While cgroups >> help, the fix is round-about at best and requires configuration where >> really none should be necessary. The easiest solution for everyone >> involved would be for rsync to use FADV_DONTNEED. The behavior doesn't >> need to be perfectly consistent between platforms for the flag to be >> useful so long as each implementation does something sane to help >> use-once access patterns. >> >> People seem to mention frequently that there are no users of >> FADV_DONTNEED and therefore we don't need to implement it. It seems like >> this is ignoring an obvious catch-22. Currently rsync has no fadvise >> support at all, since using[1] the implemented hints to get the desired >> effect is far too complicated^M^M^M^Mhacky to be considered >> merge-worthy. Considering the number of Google hits returned for >> fadvise, I wouldn't be surprised if there were countless other projects >> with this same difficulty. We want to be able to tell the kernel about >> our useage patterns, but the kernel won't listen. > > Because we have an alternative solution already. please try memcgroup :)
I think memcg could be a solution of them but fundamental solution is that we have to cure it in VM itself. I feel it's absolutely absurd to enable and use memcg for amending it.
I wonder what's the problem in Peter's patch 'drop behind'. http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg179576.html
Could anyone tell me why it can't accept upstream?
-- Kind regards, Minchan Kim -- 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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