On Fri, 12 Aug 2011 11:23:45 +0200 "Marcus Schwarz" <m.schwarz@xxxxxx> wrote: > Hi there, > > > -----Urspr$(D+d(Bngliche Nachricht----- > > Von: FUJITA Tomonori [mailto:fujita.tomonori@xxxxxxxxxxxxx] > > Gesendet: Donnerstag, 11. August 2011 16:29 > > An: Marcus Schwarz > > Cc: stgt@xxxxxxxxxxxxxxx > > Betreff: Re: bad performance maybe blocksize of LUN related > > > > > > You create a file on the file system and use it as an iSCSI logical > > unit. In such case, tgt can't use the native block size > > unconditionally. > > > > tgt is supposed to specify the block size per lun but seems the > > feature is not working correctly. I'll fix it shortly but meanwhile > > you can the following patch to use the 4096 byte block size > > unconditionally to see if you can get the performance boost. > > > > > > diff --git a/usr/sbc.c b/usr/sbc.c > > index cb07be6..0cf40be 100644 > > --- a/usr/sbc.c > > +++ b/usr/sbc.c > > @@ -41,7 +41,7 @@ > > #include "spc.h" > > #include "tgtadm_error.h" > > > > -#define DEFAULT_BLK_SHIFT 9 > > +#define DEFAULT_BLK_SHIFT 12 > > > > static unsigned int blk_shift = DEFAULT_BLK_SHIFT; > > > I applied your patch and recompiled the binarys . Now I get 30-40 MB/s in total. > > What seems a bit strange to me is that when I start the copy from my local disk to the iscsi device I'm getting around 80 MB/s up until the first GB is transfered. After that is continously dropping the transfer rate until it reaches 30 MB/s . You wrote the data to the page cache (memory) then when the page cache became full, the data went to the physical disk. -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
