Re: [Nbd] NBD Super Size io operations
Hi,
the purpose of my patch was to make the max_sectors_kb value
_adjustable_, not necessarily changing its default value although 4KB
aligned would be a bit better than 127KB...
Currently there is no way of raising the default as the
max_hw_sectors_kb is also 127KB...
Benchmarks results may vary and they do -- in my local env using my old
SSD I was getting better performance with max_sectors_kb=512 but my new
SSD shows better performance with max_sectors_kb=128 and the tests over
the network with much higher latencies may vary even more than that...
Paul, is there a chance for this and _the_ ERESTARTSYS patches got into
3.9?
On Wed, Apr 03, 2013 at 09:36:34PM +0200, folkert wrote:
> People,
>
> I did it wrong.
>
> This is correct:
>
> previously version (stock 3.8 with signal patch) with 4KB nbd, 128KB iozone3:
> random random bkwd record stride
> KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> 2097152 128 37035 38578 168336 142210 138569 36966 110692 31541 143964 53846 53114 122773 124531
>
> current version with 4KB nbd, 128KB iozone3:
> random random bkwd record stride
> KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> 2097152 128 33933 35063 116522 117882 114987 34607 116599 36000 116012 55279 55677 116960 116745
>
>
> current version with 128KB nbd, 128KB iozone3:
> random random bkwd record stride
> KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> 2097152 128 35664 35674 123922 122845 126486 36151 112671 35884 118069 53315 59279 115894 117202
>
> current version with 128KB nbd, 1024KB iozone3:
> random random bkwd record stride
> KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> 2097152 1024 33705 35078 131637 136712 136685 35152 139128 38010 148841 59181 57372 121299 113432
>
> current version with 1024KB nbd, 1024KB iozone3:
> random random bkwd record stride
> KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> 2097152 1024 34208 33322 138010 136586 136461 35383 139139 36043 131382 55621 57448 116226 117450
>
> so I don't see any logic in it
>
>
> On Tue, Apr 02, 2013 at 04:07:07PM +0200, folkert wrote:
> > I've applied the patch but I don't think I see any gain?
> >
> > now (= with that patch) with block size 1024KB:
> > random random bkwd record stride
> > KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> > 2097152 1024 35080 35989 135806 132713 134109 35615 133128 35345 139671 57022 58270 125159 131571
> >
> > now (= with that patch) with block size 128KB:
> > random random bkwd record stride
> > KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> > 2097152 128 36651 35484 112819 113962 114233 34810 113014 35782 119221 55876 54225 115214 117897
> >
> > previously version (stock 3.8 with signal patch):
> > random random bkwd record stride
> > KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
> > 2097152 128 37035 38578 168336 142210 138569 36966 110692 31541 143964 53846 53114 122773 124531
> >
> >
> > Tested using nbd-server on ramdisk, client in a vm (kernel 3.8, see above), tested with iozone3 from debian testing:
> > iozone -j 1024 -s 2g -r 128k -I -f test -+w 7
> >
> > Test system is a Linux system with kernel 2.6.38 and vmware workstation 9.
> > It has a Q9450 running at 2.1GHz and 8GB of ram with 512MB of ram for the vm.
> >
> >
> > On Mon, Apr 01, 2013 at 10:25:23PM +0200, Michal Belczyk wrote:
> > > This looks like my _other_ patch I mentioned last time (*), except that the
> > > suggested default value is different, doesn't it?
> > >
> > > (*) http://www.mail-archive.com/nbd-general@lists.sourceforge.net/msg01314.html
> > >
> > > On Mon, Apr 01, 2013 at 02:41:43PM -0400, Paul Clements wrote:
> > > > I'm looking at this right now. I just need to test and decide what the
> > > > default should be, and I'll send this upstream.
> > > >
> > > > Thanks,
> > > > Paul
> > > >
> > > > On Mon, Apr 1, 2013 at 1:45 PM, Rohan Sharma <rickyrohan14@...58...> wrote:
> > > > > My last message didn?t show up properly due to some formatting errors.
> > > > > So, I am sending it again
> > > > >
> > > > > I am using nbd over high latency network (100 ms ).
> > > > > Currently maximum size of nbd io operation(amount of data fetched in one
> > > > > request)
> > > > > I can achieve is 130kb and it gives very poor disk performance.
> > > > > I tried recompiling nbd driver code so as to increase max_sector_kb property
> > > > > of disk queue.
> > > > > I added following two lines to nbd_init function
> > > > > blk_queue_max_hw_sectors(disk->queue, 65536);
> > > > > disk->queue->limits.max_sectors = 4096;
> > > > > But these modifications changed nothing.
> > > > > Do you have any idea what can I do to increase size of nbd io operations?
> > > > > I would like it to go as high as 4MB.
> > > > >
> > > > > Thanks
> > > > >
> > > > >
> > > > >
> > > > >
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> > > Michal Belczyk Sr.
> > >
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> >
> > Folkert van Heusden
> >
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>
> Folkert van Heusden
>
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