Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-05 Thread Tomoki Sekiyama
On 8/1/13 17:04 , "Jens Axboe" wrote: >On 08/01/2013 02:28 PM, Tomoki Sekiyama wrote: >> On 7/30/13 10:09 PM, Shaohua Li wrote: >>> On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: Hi, When some application launches several hundreds of processes that issue

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-05 Thread Tomoki Sekiyama
On 8/1/13 17:04 , Jens Axboe ax...@kernel.dk wrote: On 08/01/2013 02:28 PM, Tomoki Sekiyama wrote: On 7/30/13 10:09 PM, Shaohua Li wrote: On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: Hi, When some application launches several hundreds of processes that issue only a few

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-01 Thread Jens Axboe
On 08/01/2013 02:28 PM, Tomoki Sekiyama wrote: > On 7/30/13 10:09 PM, Shaohua Li wrote: >> On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: >>> Hi, >>> >>> When some application launches several hundreds of processes that issue >>> only a few small sync I/O requests, CFQ may cause

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-01 Thread Tomoki Sekiyama
On 7/30/13 10:09 PM, Shaohua Li wrote: > On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: >> Hi, >> >> When some application launches several hundreds of processes that issue >> only a few small sync I/O requests, CFQ may cause heavy latencies >> (10+ seconds at the worst case),

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-01 Thread Tomoki Sekiyama
On 7/30/13 10:09 PM, Shaohua Li wrote: On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: Hi, When some application launches several hundreds of processes that issue only a few small sync I/O requests, CFQ may cause heavy latencies (10+ seconds at the worst case), although the

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-08-01 Thread Jens Axboe
On 08/01/2013 02:28 PM, Tomoki Sekiyama wrote: On 7/30/13 10:09 PM, Shaohua Li wrote: On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: Hi, When some application launches several hundreds of processes that issue only a few small sync I/O requests, CFQ may cause heavy latencies

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-07-30 Thread Shaohua Li
On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: > Hi, > > When some application launches several hundreds of processes that issue > only a few small sync I/O requests, CFQ may cause heavy latencies > (10+ seconds at the worst case), although the request rate is low enough for >

[RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-07-30 Thread Tomoki Sekiyama
Hi, When some application launches several hundreds of processes that issue only a few small sync I/O requests, CFQ may cause heavy latencies (10+ seconds at the worst case), although the request rate is low enough for the disk to handle it without waiting. This is because CFQ waits for

[RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-07-30 Thread Tomoki Sekiyama
Hi, When some application launches several hundreds of processes that issue only a few small sync I/O requests, CFQ may cause heavy latencies (10+ seconds at the worst case), although the request rate is low enough for the disk to handle it without waiting. This is because CFQ waits for

Re: [RFC PATCH] cfq-iosched: limit slice_idle when many busy queues are in idle window

2013-07-30 Thread Shaohua Li
On Tue, Jul 30, 2013 at 03:30:33PM -0400, Tomoki Sekiyama wrote: Hi, When some application launches several hundreds of processes that issue only a few small sync I/O requests, CFQ may cause heavy latencies (10+ seconds at the worst case), although the request rate is low enough for the