Re: Problems with VM_MIXEDMAP removal from /proc//smaps

Jeff Moyer
2018-10-16T12:35:00Z

Jan Kara <jack@suse.cz> writes:

> Hi Jeff,
>
> On Tue 09-10-18 15:43:41, Jeff Moyer wrote:
>> I'm intrigued by the use case. Do I understand you correctly that the
>> database in question does not intend to make data persistent from
>> userspace? In other words, fsync/msync system calls are being issued by
>> the database?
>
> Yes, at least at the initial stage, they use fsync / msync to persist data.

OK.

>> I guess what I'm really after is a statement of requirements or
>> expectations. It would be great if you could convince the database
>> developer to engage in this discussion directly.
>
> So I talked to them and what they really look after is the control over the
> amount of memory needed by the kernel. And they are right that if your
> storage needs page cache, the amount of memory you need to set aside for the
> kernel is larger.

OK, thanks a lot for following up, Jan!

-Jeff