25/01/12, 18:16:28
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Usuario muy activo
Mensajes: 3,224
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Fecha de registro: jul 2010
Mensajes: 3,224
Modelo de smartphone: S7 Edge
Versión de ROM: CM10 + 2.3 + ICS + 4.2.2
Tu operador: Vodafone
Mencionado: 8 comentarios
Tagged: 2 hilos
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La verdad es que al parecer los I/O scheduler son los mismos que te encuentras en Linux (dado que comparte kernel con Android). Te puedo dejar algún extracto en inglés de lo que yo indagué en su día acerca de este tema:
Cita:
Basically, the input/output scheduler works between a device and its storage drive to process reading and writing requests. It sorts and merges the read/write operations to decrease latency caused by the storage medium. Compared to the speed at which a CPU can process information, hard-disks are dreadfully slow due to their reliance on a physically moving read/write head. Lucky for us though we have a flash memory SD card that does not have moving parts.
I/O schedulers were originally intended for hard-disk type storage. A hard drive has to move the read/write heads, or seek, to the correct sector at any given time. Any time a hard-disk needs to seek, there is a large amount of latency introduced. The time it takes to process the information from a hard drive is something like millions of times faster than it takes to seek to that information (were talking nano/micro seconds though). By having the kernel sort the requests into an ascending block order, the head does not need to jump back and forth to access data, and if ordered correctly will move along a smooth path while completing its scheduled operations. This reduces the amount of time the hard drive needs to seek, which in turn reduces latency from I/O requests.
SD cards on the other hand do not have a moving read/write head like hard-disks, and remove the latency problems caused by them. Although we don't have as critical of a need for I/O scheduling, it still helps organize the reading and writing of information to the SD card and can boost performance quite noticeably. Of course certain methods of I/O scheduling were created specifically for hard-disks, and using them with an SD card wont provide the same benefits.
The three main schedulers that we see on our phones are NOOP, Deadline and CFQ.
NO-OP (no operation), does exactly what it sounds like, nothing. It does not sort or merge input/output operations and executes each operation in the order requested.
The deadline scheduler organizes the I/O operations into different first-in first-out queues for reading and writing. It will alternate between the two as needed, unless there is a certain operation that has been in queue for too long. If the in-queue time deadline is reached, then the scheduler will stop what it is doing to service that request.
CFQ stands for completely fair queue. With CFQ, each process is assigned its own queue, and each queue is assigned a time slice. The I/O scheduler visits each queue in a round-robin fashion, servicing requests from the queue until the queue’s time slice is exhausted, or until no more requests remain.
For some more in-depth information, this is a great article to read.
http://www.devshed.com/c/a/BrainDump...-Schedulers/3
Almost forgot you wanted a recommendation! Flash memory does not introduce location-dependent latency like spinning hard-disks do, so NOOP is usually a good choice to go with. It cuts out the need to process the I/O requests into queues and can speed up your phone.
Hopefully this helps. If anything here is not correct please let me know so I can correct it. Thanks!
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Cita:
Well, since I couldn't find anything pertaining to the Motorola Triumph as to what is the best IO scheduler, I decided to undertake some tests using Androbench (found on market). Tests were performed on CM7, using bkernel overclocked to 1.5GHz using smartassv2 governor.
MBSR=MB/s Sequential Read
MBSW=MB/s Sequential Write
RRIOPS=Random Reads IO's/s
RWIOPS=Random Writes IO's/s
RESULT:
Noop is overall the best in my opinion.
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entonces le pongo smartass/noop o interactive??? Gracias
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