From be49aa7ddec52e121d562e14d4d93fd301b05fbb Mon Sep 17 00:00:00 2001 From: Thomas Schwinge Date: Fri, 4 Nov 2011 19:19:35 +0100 Subject: IRC. --- hurd/libstore/examples/ramdisk/discussion.mdwn | 72 ++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 hurd/libstore/examples/ramdisk/discussion.mdwn (limited to 'hurd/libstore') diff --git a/hurd/libstore/examples/ramdisk/discussion.mdwn b/hurd/libstore/examples/ramdisk/discussion.mdwn new file mode 100644 index 00000000..d73bf903 --- /dev/null +++ b/hurd/libstore/examples/ramdisk/discussion.mdwn @@ -0,0 +1,72 @@ +[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_hurd]] + + +# IRC, freenode, #hurd, 2011-10-15 + + youpi: I'm not at all talking about ordinary tmpfs. I'm talking + about the proposed variant using a separate backing store + youpi: and as you might remember, I once came up with a crazy + passive translator command line (based on another crazy passive + translator command line from tschwinge) that can automatically do the + mkfs + so there is really very little benefit in using something else + than ext2fs when not paging to the swap partition + real tmpfs IMHO is mostly useful precisely because it uses the + ordinary swap, and doesn't have an explicit size limit... + well, it is still quite a waste to bounce data betwen page cache + and memory storage + or is ext2fs able to map the store data directly? + then there's only the medata bounce which is spurious + and still, even a one-liner settrans doesn't fit with the "is just + an fs alternative for the existing tmpfs-mounting scripts" + youpi: well, if the invocation is the major concern, it would be + trivial to write a tiny wrapper binary or script that acts like a + "normal" FS... + antrik: could you write it then? + you mean a shell script that uses ext2fs on a memory store to act + like a "proper" tmpfs? + I mean whatever that permits to just run mount none /tmp -t tmpfs + and just works already nowadays + which we could e.g. ship instead of our currently-completely bugged + tmpfs + I suspect the mount script just looks for /hurd/tmpfs in this + case? if so, that should indeed be pretty trivial. let's see if I can dig + up my crazy command line -- turning that into a "proper" script should be + quite easy I hope... + hm... I digged up + http://lists.gnu.org/archive/html/bug-hurd/2007-04/msg00013.html ; but I + wonder how much of it is really necessary for a generic pseudo-tmpfs... + the major complication seems to be the chmod, which I guess we + don't need for most use cases... + I actually don't see why it's inlined there + doesn't the caller do it if it needs it? + ah, well, here there is no caller, it's just a passive entry + is it a problem that this solution needs an extra node for the + store? + yes + because you need to say where it resides + and there's no safe place + since such safe place would typically be a mounted tmpfs + I feared that much... + I suspect we could work around this by not attaching the store to + any node; but this a) doesn't work in a shell script, and b) is much more + involved... + hm... can we assume /dev/fd to be present? I have a vague crazy + idea... + yes + I consider hacking settrans so it grows an option which allows + passing the port to the translator as an FD, instead of attaching it to + any node... this way, we could work with anonymous translators in shell + scripts :-) + (of course that's not less work than just doing the wrapper in + C... but it could be useful in other cases) -- cgit v1.2.3