Messages in this thread | | | Date | Wed, 27 Jul 2022 15:44:42 +0800 | Subject | Re: [PATCH] mm/page_owner.c: allow page_owner with given start_pfn/count | From | Kassey Li <> |
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On 7/26/2022 10:03 PM, Vlastimil Babka (SUSE) wrote: > On 7/25/22 10:39, Kassey Li wrote: >> hi, Matthew: >> sorry for the delay, I just started to learn how to upstream patch, and >> setup my Thunderbird with plain text only. >> you are right, two users will cause problem here. >> the uses case is dump CMA area to understand the page usage in a given >> cma pool. 2nd, dump whole memory page owner is very time cost, mostly our >> android device has 8G memory now. >> I will research and check again, if you have more idea on this , please >> kindly to share. > > You could try employing lseek() to specify the start pfn, and as for end > pfn, the process can just stop reading and close when it has seen enough?
lseek is a good idea. read_page_owner start with below pfn = min_low_pfn + *ppos; so we need to export the min_low_pfn to user then decide the ppos to seek. (my_cma.base_pfn - min_low_pfn) is the ppos we want to set.
is there concern to export min_low_pfn ? or use a mutex lock for my previous debugfs version patch ?
> >> BR >> Kassey >> >> On 7/22/2022 11:38 PM, Matthew Wilcox wrote: >>> On Fri, Jul 22, 2022 at 11:08:10PM +0800, Kassey Li wrote: >>>> by default, page_owner iterates all page from min_low_pfn to >>>> max_pfn, this cost too much time if we want an alternative pfn range. >>>> >>>> with this patch it allows user to set pfn range to dump the page_onwer. >>> >>> This is a really bad UI. If two users try to do different ranges at the >>> same time, it'll go wrong. What use cases are you actually trying to >>> solve? >> >
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