On Tue, Jun 9, 2020 at 4:13 AM Odin Ugedal <o...@ugedal.com> wrote: > This adds support for using non-default huge page sizes for shared > memory. This is achived via the new "huge_page_size" config entry. > The config value defaults to 0, meaning it will use the system default. > --- > > This would be very helpful when running in kubernetes since nodes may > support multiple huge page sizes, and have pre-allocated huge page meory > for each size. This lets the user select huge page size without having > to change the default huge page size on the node. This will also be > useful when doing benchmarking with different huge page sizes, since it > wouldn't require a full system reboot.
+1 > Since the default value of the new config is 0 (resulting in using the > default huge page size) this should be backwards compatible with old > configs. +1 > Feel free to comment on the phrasing (both in docs and code) and on the > overall change. This change seems good to me, because it will make testing easier and certain mixed page size configurations possible. I haven't tried your patch yet; I'll take it for a spin when I'm benchmarking some other relevant stuff soon. Minor comments on wording: > + <para> > + Most modern linux systems support <literal>2MB</literal> and > <literal>1GB</literal> > + huge pages, and some architectures supports other sizes as well. For > more information > + on how to check for support and usage, see <xref > linkend="linux-huge-pages"/>. Linux with a capital L. Hmm, I don't especially like saying "Most modern Linux systems" as code for Intel. I wonder if we should instead say something like: "Some commonly available page sizes on modern 64 bit server architectures include: <literal>2MB<literal> and <literal>1GB</literal> (Intel and AMD), <literal>16MB</literal> and <literal>16GB</literal> (IBM POWER), and ... (ARM)." > + </para> > + <para> > + Controling huge page size is not supported on Windows. Controlling Just by the way, some googling is telling me that very recent versions of Windows *could* support this (search keywords: "NtAllocateVirtualMemoryEx 1GB"), so that could be a project for someone who understands Windows to look into later.