Re: [ledbat] list of reasons for needing multiple TCP connections
Murari Sridharan <muraris@microsoft.com> Wed, 26 November 2008 00:55 UTC
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From: Murari Sridharan <muraris@microsoft.com>
To: Joe Touch <touch@ISI.EDU>, "Kartik Chandrayana (karchand)" <karchand@cisco.com>
Date: Tue, 25 Nov 2008 16:55:21 -0800
Thread-Topic: [ledbat] list of reasons for needing multiple TCP connections
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Subject: Re: [ledbat] list of reasons for needing multiple TCP connections
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I am not sure I get the entire context of Kartik's comment but Windows Server supports a feature called Receive-side scaling which essentially distributes receive processing and tries to spread TCP connections across multiple cores and tries to keep all processing for a connection aligned on one specific CPU (to the extent that apps cooperate) starting with packet indication all the way to deliver to the app. Connections can get moved around depending on load but in steady state they should remain pinned with the some caveats. Some links http://download.microsoft.com/download/a/d/f/adf1347d-08dc-41a4-9084-623b1194d4b2/RSS_Server2008.docx http://msdn.microsoft.com/en-us/library/ms795616.aspx Thanks -----Original Message----- From: ledbat-bounces@ietf.org [mailto:ledbat-bounces@ietf.org] On Behalf Of Joe Touch Sent: Thursday, November 20, 2008 12:57 PM To: Kartik Chandrayana (karchand) Cc: ledbat@ietf.org Subject: Re: [ledbat] list of reasons for needing multiple TCP connections -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Kartik Chandrayana (karchand) wrote: > Joe, > > I am also not aware if parallelization of network code is implemented > in OSes. However, I think it would be reasonable to expect that tcpcb > lookups are done in a centralized fashion and once that is done, > multiple tcp's can be processed in different cpus. Even the lookups can > be distributed as they are only a read operation. Parallelizing TCP includes dealing with not only the TCP code, but also the IP input queue access, timers, etc. I am not as sure that there's a one TCP per core mapping in current OS's - though I'd be glad to hear someone *confirm* it. Joe > -----Original Message----- > From: Joe Touch [mailto:touch@ISI.EDU] > Sent: Thursday, November 20, 2008 2:44 PM > To: Kartik Chandrayana (karchand) > Cc: Andrew G. Malis; ledbat@ietf.org > Subject: Re: [ledbat] list of reasons for needing multiple TCP > connections > > > > Kartik Chandrayana (karchand) wrote: >> Andy, Joe: > >> One reason I can think of using multiple TCP connections is to >> overcome the non-negotiation of window-scale parameter on most boxes. >> With default window scale parameters, i.e 0, the congestion window is >> limited to 64KB only and thus for any pipe with >> bandwidth-delay-product greater than 64KB, a single TCP connection >> cannot keep the pipe full. In such a case, it would be beneficial to > have multiple TCP connections. >> Also, since TCP design was mostly with single cpu in mind, I think >> multiple TCP connections can harness the multi-cpu architectures >> better than a single lean fast TCP. > > That presumes that the OS implements parallelization in the network > code; I don't know if that's recently offered, but it has been the > sticking point in the past. > > Joe -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkklzy0ACgkQE5f5cImnZrtxIwCgw+uW7JxMRDZja1pTuixQUwS8 m5IAoPHHCB2ed20zXkkv15m09kF4q+mm =30jd -----END PGP SIGNATURE----- _______________________________________________ ledbat mailing list ledbat@ietf.org https://www.ietf.org/mailman/listinfo/ledbat _______________________________________________ ledbat mailing list ledbat@ietf.org https://www.ietf.org/mailman/listinfo/ledbat
- [ledbat] list of reasons for needing multiple TCP… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Andrew G. Malis
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Kartik Chandrayana (karchand)
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Kartik Chandrayana (karchand)
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… lars.eggert
- Re: [ledbat] list of reasons for needing multiple… Caitlin Bestler
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Caitlin Bestler
- Re: [ledbat] list of reasons for needing multiple… Reinaldo Penno
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Joe Touch
- Re: [ledbat] list of reasons for needing multiple… Bryan Ford
- Re: [ledbat] list of reasons for needing multiple… Michael Welzl
- Re: [ledbat] list of reasons for needing multiple… Stanislav Shalunov
- Re: [ledbat] list of reasons for needing multiple… Stanislav Shalunov
- Re: [ledbat] list of reasons for needing multiple… Stanislav Shalunov
- Re: [ledbat] list of reasons for needing multiple… Reinaldo Penno
- Re: [ledbat] list of reasons for needing multiple… Stanislav Shalunov
- Re: [ledbat] list of reasons for needing multiple… Murari Sridharan
- Re: [ledbat] list of reasons for needing multiple… Reinaldo Penno
- Re: [ledbat] list of reasons for needing multiple… Stanislav Shalunov
- Re: [ledbat] list of reasons for needing multiple… Murari Sridharan
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Lars Eggert
- Re: [ledbat] list of reasons for needing multiple… Richard Bennett
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Richard Bennett
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Richard Bennett
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Richard Bennett
- Re: [ledbat] list of reasons for needing multiple… Nicholas Weaver
- Re: [ledbat] list of reasons for needing multiple… Reinaldo Penno
- Re: [ledbat] list of reasons for needing multiple… Eric Spaeth
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski
- Re: [ledbat] list of reasons for needing multiple… Robb Topolski