On Thu, Feb 27, 2020 at 1:57 PM Richard Henderson <
address@hidden> wrote:
On 2/27/20 4:31 AM, Alex Bennée wrote:
>> It does not make sense for a linux-user chroot, running make -jN, on just about
>> any host. For linux-user, I could be happy with a modest increase, but not all
>> the way out to 2GiB.
>>
>> Discuss.
>
> Does it matter that much? Surely for small programs the kernel just
> never pages in the used portions of the mmap?
That's why I used the example of a build under the chroot, because the compiler
is not a small program.
Consider when the memory *is* used, and N * 2GB implies lots of paging, where
the previous N * 32MB did not.
I agree that a lower default value probably is safer until we have more proof that a larger value does not give any issues.
I'm saying that we should consider a setting more like 128MB or so, since the
value cannot be changed from the command-line, or through the environment.
Proposal: can we then introduce a new command line parameter for this? Maybe in a new patch?
Since the size of the code generation buffer appears to have an impact on performance,
in my opinion it would make sense to make it configurable by the user.
Regards,
Niek
r~