Messages in this thread | | | Date | Fri, 7 Oct 2011 17:55:00 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings |
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On Fri, 7 Oct 2011 12:20:04 +0400 Glauber Costa <glommer@parallels.com> wrote:
> > > >> So what I really mean here with "will integrate later", is that I think > >> that we'd be better off tracking the allocations themselves at the slab > >> level. > >> > >>> Can't tcp-limit-code borrows some amount of charges in batch from kmem_limit > >>> and use it ? > >> Sorry, I don't know what exactly do you mean. Can you clarify? > >> > > Now, tcp-usage is independent from kmem-usage. > > > > My idea is > > > > 1. when you account tcp usage, charge kmem, too. > > Absolutely. > > Now, your work is > > a) tcp use new xxxx bytes. > > b) account it to tcp.uage and check tcp limit > > > > To ingegrate kmem, > > a) tcp use new xxxx bytes. > > b) account it to tcp.usage and check tcp limit > > c) account it to kmem.usage > > > > ? 2 counters may be slow ? > > Well, the way I see it, 1 counter is slow already =) > I honestly think we need some optimizations here. But > that is a side issue. > > To begin with: The new patchset that I intend to spin > today or Monday, depending on my progress, uses res_counters, > as you and Kirill requested. > > So what makes res_counters slow IMHO, is two things: > > 1) interrupts are always disabled. > 2) All is done under a lock. > > Now, we are starting to have resources that are billed to multiple > counters. One simple way to work around it, is to have child counters > that has to be accounted for as well everytime a resource is counted. > > Like this: > > 1) tcp has kmem as child. When we bill to tcp, we bill to kmem as well. > For protocols that do memory pressure, we then don't bill kmem from > the slab. > 2) When kmem_independent_account is set to 0, kmem has mem as child. >
Seems reasonable.
> > > > > >>> - Don't you need a stat file to indicate "tcp memory pressure works!" ? > >>> It can be obtained already ? > >> > >> Not 100 % clear as well. We can query the amount of buffer used, and the > >> amount of buffer allowed. What else do we need? > >> > > > > IIUC, we can see the fact tcp.usage is near to tcp.limit but never can see it > > got memory pressure and how many numbers of failure happens. > > I'm sorry if I don't read codes correctly. > > IIUC, With res_counters being used, we get at least failcnt for free, right? >
Right. you can get failcnt and max_usage and can have soft_limit base implemenation at the same time.
Thank you. -Kame
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