On 11 December 2012 19:33:39 Edward Shishkin wrote:
> On 12/11/2012 04:08 PM, Ivan Shapovalov wrote:
> > Hello!
>
> Hello.
>
> > With help of Dušan Čolić <dusanc@xxxxxxxxx> who provided his kernel config
> > diff I've found a kernel option which, when disabled, greatly reduces
> > (hopefully to zero, but need time to verify it) corruption rate in
> > reiser4.
> >
> > It's CONFIG_TRANSPARENT_HUGEPAGE (or something which is used by it like
> > CONFIG_COMPACTION or CONFIG_MIGRATION).
> > For now I'm testing it with CONFIG_TRANSPARENT_HUGEPAGE disabled
>
> How long?
12 hours of indexing, scanning, compiling, repeated execution of
"find <mountpoint> -type f -exec grep wtf {} \;" and so on.
>
> > on kernel
> >
> > 3.6.10, and everything seems to be OK so far (so the workaround is
> > version-
> > agnostic).
> >
> > Edward, are there any guesses on what can make reiser4 choke on
> > hugepages/compaction/migration?
>
> TBH, no ideas. They (hugepages) are _transparent_.
> It means we shouldn't suffer in theory ;)
Maybe it's actually migration who does the damage? If we don't lock the pages
properly and they are "stolen" by the migration code... If this is the case, I
shall eventually get corruptions with current setup (since
migration/compaction is not disabled).
If I get them, I'll rebuild without migration at all and will see if
corruptions disappear completely. (Then they should disappear, if the
prediction is true.)
>
> > I'm not even barely familiar with the kernel
> >
> > internals.
> >
> > Thanks,
> > Ivan.
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