How to avoid or reduce GFP_ATOMIC allocation failed
Hi, I check kernel code and found that GFP_ATOMIC allocation will use emergency pool and maybe failed if emergency pool is not enough. And GFP_ATOMIC doesn't trigger reclaim (because of ATOMIC) even if there are a lot of page caches. So my question is how to avoid or reduce GFP_ATOMIC allocation failed if there are enough reclaimable memory? Is there some kernel parameters can be configured? Thanks.
On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
Hi,
I check kernel code and found that GFP_ATOMIC allocation will use emergency pool and maybe failed if emergency pool is not enough. And GFP_ATOMIC doesn't trigger reclaim (because of ATOMIC) even if there are a lot of page caches. So my question is how to avoid or reduce GFP_ATOMIC allocation failed if there are enough reclaimable memory? Is there some kernel parameters can be configured?
Have you seen the ATOMIC pools be used up and not able to be reclaimed in real-world usages? If so, I'm sure the mm developers would love to hear from you about this as I really do not think that is a situation that can happen easily, if at all. And no, I do not think there are any such parameters, the kernel should be self-tuning for things like this. thanks, greg k-h
-----Original Messages----- From: "Greg KH" <greg@kroah.com> Sent Time: 2019-03-08 15:21:52 (Friday) To: wuzhouhui <wuzhouhui14@mails.ucas.ac.cn> Cc: kernelnewbies@kernelnewbies.org Subject: Re: How to avoid or reduce GFP_ATOMIC allocation failed
On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
Hi,
I check kernel code and found that GFP_ATOMIC allocation will use emergency pool and maybe failed if emergency pool is not enough. And GFP_ATOMIC doesn't trigger reclaim (because of ATOMIC) even if there are a lot of page caches. So my question is how to avoid or reduce GFP_ATOMIC allocation failed if there are enough reclaimable memory? Is there some kernel parameters can be configured?
Have you seen the ATOMIC pools be used up and not able to be reclaimed in real-world usages? If so, I'm sure the mm developers would love to
No, I haven't seen this scenario. But I encountered the similar issue with [1] (order is 5 in my scenario), and this issue is not resolved for now. Thanks. [1] https://stackoverflow.com/questions/53936183/linux-disk-cache-and-kmalloc-wi...
hear from you about this as I really do not think that is a situation that can happen easily, if at all.
And no, I do not think there are any such parameters, the kernel should be self-tuning for things like this.
thanks,
greg k-h
On Fri, Mar 08, 2019 at 03:34:18PM +0800, wuzhouhui wrote:
-----Original Messages----- From: "Greg KH" <greg@kroah.com> Sent Time: 2019-03-08 15:21:52 (Friday) To: wuzhouhui <wuzhouhui14@mails.ucas.ac.cn> Cc: kernelnewbies@kernelnewbies.org Subject: Re: How to avoid or reduce GFP_ATOMIC allocation failed
On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
Hi,
I check kernel code and found that GFP_ATOMIC allocation will use emergency pool and maybe failed if emergency pool is not enough. And GFP_ATOMIC doesn't trigger reclaim (because of ATOMIC) even if there are a lot of page caches. So my question is how to avoid or reduce GFP_ATOMIC allocation failed if there are enough reclaimable memory? Is there some kernel parameters can be configured?
Have you seen the ATOMIC pools be used up and not able to be reclaimed in real-world usages? If so, I'm sure the mm developers would love to
No, I haven't seen this scenario. But I encountered the similar issue with [1] (order is 5 in my scenario), and this issue is not resolved for now.
Please work with the company that created your out-of-tree kernel networking code as it sounds like they do not know how to properly handle this type of problem :) good luck! greg k-h
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wuzhouhui