Messages in this thread | | | Date | Wed, 27 Oct 1999 14:46:46 -0400 (EDT) | From | Alexander Viro <> | Subject | Re: Question on the VFS inode structure. |
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On Wed, 27 Oct 1999, Malcolm Beattie wrote:
> I don't remember exactly what you proposed for this, but if you are > intending to replace the inode structure with a generic one which has > a pointer to a separately allocated per-fs structure then here's a > warning. Digital UNIX used to that but had to change it exactly the > opposite way for performance reasons. Its vnode structure used to > have a v_data pointer to a separately allocated per-fs "private" > structure. However, performance was bad because of the pointer > following and the extra fragmentation. They ended up reuniting the two
Ouch. From what I've seen in Vahalia they seem to be doing ungodly amount of directory accesses - even worse than 4.4BSD. Completely different load _and_ mix. So I seriously doubt that we can apply their data.
> so that they could allocate the whole (generic + private) structure in > one chunk and then made v_data point to directly after the generic > part (i.e. the start of the no-longer-separate private part). > > They did the same with their ungodly mixture of BSD and Mach > structures for tasks and threads: they had separate struct task, > struct proc and struct utask which they combined into a single struct > super_task (though still with pointers between the supposedly > "separate" bits) and they had separate struct thread and struct > np_uthread which they combined into struct super_thread.
<shudder>
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