Re: [PATCH 00/15] Swap-over-NBD without deadlocking V8

On Wed, Feb 08, 2012 at 08:51:11PM +0800, Hillf Danton wrote:

On Tue, Feb 7, 2012 at 9:27 PM, Mel Gorman [off-list ref] wrote:

quoted

On Tue, Feb 07, 2012 at 08:45:18PM +0800, Hillf Danton wrote:

quoted

If it is feasible to bypass hang by tuning min_mem_kbytes,

No. Increasing or descreasing min_free_kbytes changes the timing but it
will still hang.

quoted

things may
become simpler if NICs are also tagged.

That would mean making changes to every driver and they do not necessarily
know what higher level protocol like TCP they are transmitting. How is
that simpler? What is the benefit?

The benefit is to avoid allocating sock buffer in softirq by recycling,
then the changes in VM core maybe less.

The VM is responsible for swapping. It's reasonable that the core
VM has responsibility for it without trying to shove complexity into
drivers or elsewhere unnecessarily. I see some benefit in following on
by recycling some skbs and only allocating from softirq if no recycled
skbs are available.  That potentially improves performance but I do not
recycling as a replacement.

-- 
Mel Gorman
SUSE Labs

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