On Thu, Jul 9, 2009 at 4:55 PM, Ulrich Drepper <drep...@redhat.com> wrote:
> Adam Miller wrote: > > I am curious as to this answer as well because prelink has been > > something that actually hurt my netbook in performance so I nuked it. > > Performance only ever can be hurt because prelink runs periodically to > prelink newly installed code or re-randomize to increase security. > > prelink has two benefits: > > - almost all relocations a program has to perform are avoided. These > can be very expensive when many dependencies and/or large symbol > tables are involved. The latter is somewhat mitigated by the new > symbol table hashing we implemented some time back but still. > > - as a side effect of the first point some pages in the loaded binary > are not copied-on-write. This can obviously have good effects on > systems with little memory (netbooks). > > > Just run your own tests on apps with many relocations and dependencies. > FF, OO.org, most GUI apps come into mind. Use > > LD_DEBUG=statistics some/program > > to compare numbers. Run it with and without prelink (but always with > hot disk cache to be fair). The number of cycles for total startup is > representative of the win. > > Note, also small but frequently used apps benefit. I run gcc etc a lot > and like every single saved cycle. > But something one have to pay a security prize on not disabling it : it render impossible to have a centralizzated security integrity management (e.g. rfc.sf.net for example) or one have to skip from check the prelink binary. Very bad i think. > > -- > ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ > > -- > fedora-devel-list mailing list > fedora-devel-list@redhat.com > https://www.redhat.com/mailman/listinfo/fedora-devel-list >
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