Messages in this thread | | | Date | Wed, 18 Jan 2012 09:16:49 +0200 (EET) | From | Pekka Enberg <> | Subject | Re: [RFC 1/3] /dev/low_mem_notify |
| |
On Wed, 18 Jan 2012, Minchan Kim wrote: > I didn't look into your code(will do) but as I read description, > still I don't convince we need really some process specific threshold like 99% > I think application can know it by polling /proc/meminfo without this mechanism > if they really want.
I'm not sure if we need arbitrary threshold either. However, we need to support the following cases:
- We're about to swap
- We're about to run out of memory
- We're about to start OOM killing
and I don't think your patch solves that. One possibility is to implement:
VMNOTIFY_TYPE_ABOUT_TO_SWAP VMNOTIFY_TYPE_ABOUT_TO_OOM VMNOTIFY_TYPE_ABOUT_TO_OOM_KILL
and maybe rip out support for arbitrary thresholds. Does that more reasonable?
As for polling /proc/meminfo, I'd much rather deliver stats as part of vmnotify_read() because it's easier to extend the ABI rather than adding new fields to /proc/meminfo.
On Wed, 18 Jan 2012, Minchan Kim wrote: > I would like to notify when system has a trobule with memory pressure without > some process specific threshold. Of course, applicatoin can't expect it.(ie, > application can know system memory pressure by /proc/meminfo but it can't know > when swapout really happens). Kernel low mem notify have to give such notification > to user space, I think.
It should be simple to add support for VMNOTIFY_TYPE_MEM_PRESSURE that uses your hooks.
Pekka
| |