[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for-xen-4.5] console: increase initial conring size
On Tue, Dec 02, 2014 at 03:58:53PM +0000, Jan Beulich wrote: > >>> Daniel Kiper <daniel.kiper@xxxxxxxxxx> 12/02/14 3:58 PM >>> > >In general initial conring size is sufficient. However, if log > >level is increased on platforms which have e.g. huge number > >of memory regions (I have an IBM System x3550 M2 with 8 GiB RAM > >which has more than 200 entries in EFI memory map) then some > >of earlier messages in console ring are overwritten. It means > >that in case of issues deeper analysis can be hindered. Sadly > >conring_size argument does not help because new console buffer > >is allocated late on heap. It means that it is not possible to > >allocate larger ring earlier. So, in this situation initial > >conring size should be increased. My experiments showed that > >even on not so big machines more than 26 KiB of free space are > >needed for initial messages. In theory we could increase conring > >size buffer to 32 KiB. However, I think that this value could be > >too small for huge machines with large number of ACPI tables and > >EFI memory regions. Hence, this patch increases initial conring > >size to 64 KiB. > > > >Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx> > > I think it was made clear before that just saying "for-xen-4.5" without any > further rationale is insufficient. Please explain what makes this so important > a change that it needs to go in now. What is not clear in commit message? It describes a bug, how to fix it and why in that way. Do you need anything else? > Apart from that, as Olaf validly replied, setting up a dynamically allocated > buffer earlier would seem like a much better course of action. I though about that before posting this patch (I did not know beforehand about Olaf's work made in 2011). However, I stated that it is too late to make so intrusive changes. I think we should (sadly) apply this "band-aid" right now because, as you can see, this bug hits more and more people. On the other hand I agree that we should finally fix this issue in better way. Even I am able to add this thing to my TODO list but it is quite long so I do not know when it will happen. Daniel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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