Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-10 Thread Namjae Jeon
2013/1/10 Jan Kara : > On Wed 09-01-13 17:26:36, Namjae Jeon wrote: > >> But in one normal scenario, the changes actually results in >> performance degradation. >> >> Results for ‘dd’ thread on two devices: >> Before applying Patch: >> #> dd if=/dev/zero of=/mnt/sdb2/file1 bs=1048576 count=800 & >

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-09 Thread Jan Kara
On Wed 09-01-13 17:26:36, Namjae Jeon wrote: > But in one normal scenario, the changes actually results in > performance degradation. > > Results for ‘dd’ thread on two devices: > Before applying Patch: > #> dd if=/dev/zero of=/mnt/sdb2/file1 bs=1048576 count=800 & > #> dd if=/dev/zero of=/mnt/sd

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-09 Thread Namjae Jeon
> > Yeah, that IO pattern is not good. Perhaps it's 6 small IOs in /one/ > second? However that's not quite in line with "sleep 2sec" in your > workload description. Note that I assume flush-8:0 works on a hard > disk, so each flush-8:0 line indicates roughly 1 second interval > elapsed. It would

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-05 Thread Fengguang Wu
On Sat, Jan 05, 2013 at 03:41:54AM -0600, Simon Jeons wrote: > On Sat, 2013-01-05 at 15:38 +0800, Fengguang Wu wrote: > > On Fri, Jan 04, 2013 at 11:26:43PM -0600, Simon Jeons wrote: > > > On Sat, 2013-01-05 at 11:26 +0800, Fengguang Wu wrote: > > > > > > > Hi Namjae, > > > > > > > > > > > > > > Wh

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-05 Thread Simon Jeons
On Sat, 2013-01-05 at 15:38 +0800, Fengguang Wu wrote: > On Fri, Jan 04, 2013 at 11:26:43PM -0600, Simon Jeons wrote: > > On Sat, 2013-01-05 at 11:26 +0800, Fengguang Wu wrote: > > > > > > Hi Namjae, > > > > > > > > > > > > Why use bdi_stat_error here? What's the meaning of its comment > > > > > >

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-04 Thread Fengguang Wu
On Fri, Jan 04, 2013 at 11:26:43PM -0600, Simon Jeons wrote: > On Sat, 2013-01-05 at 11:26 +0800, Fengguang Wu wrote: > > > > > Hi Namjae, > > > > > > > > > > Why use bdi_stat_error here? What's the meaning of its comment > > > > > "maximal > > > > > error of a stat counter"? > > > > Hi Simon, > >

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-04 Thread Simon Jeons
On Sat, 2013-01-05 at 11:26 +0800, Fengguang Wu wrote: > > > > Hi Namjae, > > > > > > > > Why use bdi_stat_error here? What's the meaning of its comment "maximal > > > > error of a stat counter"? > > > Hi Simon, > > > > > > As you know bdi stats (BDI_RECLAIMABLE, BDI_WRITEBACK …) are kept in > > >

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-04 Thread Fengguang Wu
> > > Hi Namjae, > > > > > > Why use bdi_stat_error here? What's the meaning of its comment "maximal > > > error of a stat counter"? > > Hi Simon, > > > > As you know bdi stats (BDI_RECLAIMABLE, BDI_WRITEBACK …) are kept in > > percpu counters. > > When these percpu counters are incremented/decrem

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-04 Thread Fengguang Wu
Hi Namjae, On Sun, Dec 30, 2012 at 02:59:50PM +0900, Namjae Jeon wrote: > From: Namjae Jeon > > Consider Process A: huge I/O on sda > doing heavy write operation - dirty memory becomes more > than dirty_background_ratio > on HDD - flusher thread flush-8:0 > > Consider Pr

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-04 Thread Simon Jeons
On Fri, 2013-01-04 at 16:41 +0900, Namjae Jeon wrote: > 2013/1/4, Simon Jeons : > > On Thu, 2013-01-03 at 13:35 +0900, Namjae Jeon wrote: > >> 2013/1/2, Jan Kara : > >> > On Tue 01-01-13 08:51:04, Wanpeng Li wrote: > >> >> On Mon, Dec 31, 2012 at 12:30:54PM +0100, Jan Kara wrote: > >> >> >On Sun 30

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-03 Thread Namjae Jeon
2013/1/4, Simon Jeons : > On Thu, 2013-01-03 at 13:35 +0900, Namjae Jeon wrote: >> 2013/1/2, Jan Kara : >> > On Tue 01-01-13 08:51:04, Wanpeng Li wrote: >> >> On Mon, Dec 31, 2012 at 12:30:54PM +0100, Jan Kara wrote: >> >> >On Sun 30-12-12 14:59:50, Namjae Jeon wrote: >> >> >> From: Namjae Jeon >>

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-03 Thread Simon Jeons
On Thu, 2013-01-03 at 13:35 +0900, Namjae Jeon wrote: > 2013/1/2, Jan Kara : > > On Tue 01-01-13 08:51:04, Wanpeng Li wrote: > >> On Mon, Dec 31, 2012 at 12:30:54PM +0100, Jan Kara wrote: > >> >On Sun 30-12-12 14:59:50, Namjae Jeon wrote: > >> >> From: Namjae Jeon > >> >> > >> >> Consider Process

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-02 Thread Namjae Jeon
2013/1/2, Jan Kara : > On Tue 01-01-13 08:51:04, Wanpeng Li wrote: >> On Mon, Dec 31, 2012 at 12:30:54PM +0100, Jan Kara wrote: >> >On Sun 30-12-12 14:59:50, Namjae Jeon wrote: >> >> From: Namjae Jeon >> >> >> >> Consider Process A: huge I/O on sda >> >> doing heavy write operation - dirty

Re: [PATCH] writeback: fix writeback cache thrashing

2013-01-02 Thread Jan Kara
On Tue 01-01-13 08:51:04, Wanpeng Li wrote: > On Mon, Dec 31, 2012 at 12:30:54PM +0100, Jan Kara wrote: > >On Sun 30-12-12 14:59:50, Namjae Jeon wrote: > >> From: Namjae Jeon > >> > >> Consider Process A: huge I/O on sda > >> doing heavy write operation - dirty memory becomes more > >>

Re: [PATCH] writeback: fix writeback cache thrashing

2012-12-31 Thread Jan Kara
On Sun 30-12-12 14:59:50, Namjae Jeon wrote: > From: Namjae Jeon > > Consider Process A: huge I/O on sda > doing heavy write operation - dirty memory becomes more > than dirty_background_ratio > on HDD - flusher thread flush-8:0 > > Consider Process B: small I/O on sdb >

[PATCH] writeback: fix writeback cache thrashing

2012-12-29 Thread Namjae Jeon
From: Namjae Jeon Consider Process A: huge I/O on sda doing heavy write operation - dirty memory becomes more than dirty_background_ratio on HDD - flusher thread flush-8:0 Consider Process B: small I/O on sdb doing while [1]; read 1024K + rewrite 1024K + sleep 2se