| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Sat, 21 Aug 2010 23:07:32 +0200 From: Corrado Zoccolo <czoccolo@...il.com> To: Pedro Eugênio Rocha <pedro.eugenio.rocha@...il.com> Cc: linux-kernel@...r.kernel.org Subject: Re: Using block layer's I/O context api (block/blk-ioc.c) without CFQ. 2010/8/21 Pedro Eugênio Rocha <pedro.eugenio.rocha@...il.com>: > Thanks for your reply, > > 2010/8/20 Corrado Zoccolo <czoccolo@...il.com>: >> 2010/8/19 Pedro Eugênio Rocha <pedro.eugenio.rocha@...il.com>: >>> Hi, >> Hi, >>> >>> Is there a way to use the generic block layer I/O context api >>> (block/blk-ioc.c), without >>> using cfq specific functions and structs? I'm writing an I/O scheduler >>> for my master >>> thesis, and I'd like to use my own functions for I/O context handling, >>> not cfq's. Sorry >>> if I'm missing something here. >> Sure. I think you can get an idea by grabbing an old enough kernel >> that still has anticipatory scheduler (if I recall correctly, 2.6.32 >> should have it), and look at its functions. > > In mainstream kernel as in 2.6.32, it's used a generic get_io_context > function to get the current task io_context. In addition, you can create > a function like cfq_get_io_context to implement some scheduler > specific stuff. Oh right so far. > > But when the task is exiting there is an exit_io_context function, which > calls put_io_context. This function calls cfq_dtor, which seems to be > an specific cfq function, and maybe will not work with others I/O > schedulers. My newbie question is, those block/blk-ioc.c functions > are supposed to be generic, or my scheduler should implement it's > own? Cfq and AS required extending the basic io_context to add per-process statistics. Therefore, cfq_io_context and as_io_context were added to the io_context, and proper deallocation is done when deallocating io_context (as_io_context is deallocated via its dtor function pointer just before calling cfq_dtor). If your I/O scheduler requires storing some stats per process, you have the choice of either reusing one of the existing as/cfq io_context extensions, or define your own (and in that case, you should add your destructor as well). > > >> Or you can look at my post: >> http://lists.openwall.net/linux-kernel/2009/06/08/387, where I >> implemented a proof-of-concept I/O scheduler based on anticipatory >> scheduler. Most of the concepts in that scheduler were later ported to >> CFQ. >> Do you already have a scheduling algorithm in mind? And what will be >> your main purpose/target? >> > > Yes. Our main purpose is to share disk I/O bandwidth among > processes/tasks/cgroups/whatever providing strong QoS guarantees, such > as bandwidth, bursts and latency. It borrows many ideas from bfq and > pClock I/O schedulers. The implementation will be just a proof-of-concept, > not something you can use in a real environment. =) Sounds interesting. Do you plan to have simulations before the real implementation, and what are your reference workloads? Cheers, Corrado > Thanks for your help! > >> Thanks >> Corrado >>> >>> Thanks, >>> >>> Pedro Eugênio Rocha >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>> the body of a message to majordomo@...r.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> Please read the FAQ at http://www.tux.org/lkml/ >>> >> >> >> >> -- >> __________________________________________________________________________ >> >> dott. Corrado Zoccolo mailto:czoccolo@...il.com >> PhD - Department of Computer Science - University of Pisa, Italy >> -------------------------------------------------------------------------- >> The self-confidence of a warrior is not the self-confidence of the average >> man. The average man seeks certainty in the eyes of the onlooker and calls >> that self-confidence. The warrior seeks impeccability in his own eyes and >> calls that humbleness. >> Tales of Power - C. Castaneda >> > > > > -- > Pedro Eugênio Rocha > -- __________________________________________________________________________ dott. Corrado Zoccolo mailto:czoccolo@...il.com PhD - Department of Computer Science - University of Pisa, Italy -------------------------------------------------------------------------- The self-confidence of a warrior is not the self-confidence of the average man. The average man seeks certainty in the eyes of the onlooker and calls that self-confidence. The warrior seeks impeccability in his own eyes and calls that humbleness. Tales of Power - C. Castaneda -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists