Messages in this thread | ![/](/images/icornerl.gif) | | From | Badari Pulavarty <> | Subject | Re: [patch for playing] 2.5.65 patch to support > 256 disks | Date | Mon, 24 Mar 2003 14:54:03 -0800 |
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On Monday 24 March 2003 02:22 pm, Douglas Gilbert wrote: > Badari Pulavarty wrote: > > On Saturday 22 March 2003 04:05 am, Andrew Morton wrote: > >>OK, thanks. So with 48 disks you've lost five megabytes to > >> blkdev_requests and deadline_drq objects. With 4000 disks, you're > >> toast. That's enough request structures to put 200 gigabytes of memory > >> under I/O ;) > >> > >>We need to make the request structures dymanically allocated for other > >>reasons (which I cannot immediately remember) but it didn't happen. I > >>guess we have some motivation now. > > > > Here is the list of slab caches which consumed more than 1 MB > > in the process of inserting 4000 disks. > > > > #insmod scsi_debug.ko add_host=4 num_devs=1000 > > > > deadline_drq before:1280 after:1025420 diff:1024140 size:64 > > incr:65544960 blkdev_requests before:1280 after:1025400 diff:1024120 > > size:156 incr:159762720 > > > > * deadline_drq, blkdev_requests consumed almost 80 MB. We need to fix > > this. > > > > inode_cache before:700 after:140770 diff:140070 size:364 > > incr:50985480 dentry_cache before:4977 after:145061 diff:140084 > > size:172 incr:24094448 > > > > * inode cache increased by 50 MB, dentry cache 24 MB. > > It looks like we cached 140,000 inodes. I wonder why ? > > > > <snip/> > > Badari, > What number do you get from > # cd /sys; du -a | wc > when you have 4000 disks?
[root@elm3b78 sysfs]# du -a | wc -l 140735
Okay. That explains the inodes.
> > Also scsi_debug should use only 8 MB (default) for > simulated storage shared between all pseudo disks > (i.e. not 8 MB per simulated host).
Hmm. When I did insmod scsi_debug.o add_host=1 num_devs=4000 it used 8MB.
But when I did insmod scsi_debug.o add_host=4 num_devs=1000 it used 32 MB. So I assumed it is per host.
Before: size-8192 8 8 8192 8 8 2 : 8 4 : 9 12 10 2 0 0 37 : 3 12 7 0 After: size-8192 4010 4010 8192 4010 4010 2 : 8 4 : 4010 4014 4012 2 0 0 37 : 4006 4014 4011 0
Thanks, Badari
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