Hello, thanks for the answer. Maybe I sound stupid but how can I tell g_mass_storage which controller to use? If I unload dummy_hcd and then try to modprobe g_mass_storage I get an error "no such device". # lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 003: ID 046d:c050 Logitech, Inc. RX 250 Optical Mouse Bus 002 Device 004: ID 046d:c31d Logitech, Inc. Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Thanks in advance. -- Victor On Thu, Sep 5, 2013 at 5:58 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 5 Sep 2013, Victor Leschuk wrote: > >> Hello all, >> >> I have recently faced a performance problem with usb gadget emulated >> USB flash drive. It is working fine except for very low performance. >> >> I use a 4Gb file, created by dd and created a ext2 or vfat (tried >> both) partition on it. Than I mount it using the following command >> sequence: >> >> ------------------------------ >> # modprobe dummy_hcd is_super_speed=1 # I tried is_high_speed=1, and >> no parameter too >> # modprobe g_mass_storage file=/home/del/img/flash stall=0 # tried w/o >> stall=0 too >> # mount /dev/sdc1 /mnt/tmp >> ------------------------------ >> >> After that I get /dev/sdc and /dev/sdc1 devices created without any >> errors in dmesg: >> >> ------------------------------ >> [1256700.986581] usb 3-1: reset high-speed USB device number 5 using dummy_hcd >> [1256701.022551] gadget: high-speed config #1: Linux File-Backed Storage >> [1256701.242481] usb 3-1: reset high-speed USB device number 5 using dummy_hcd >> [1256701.278422] gadget: high-speed config #1: Linux File-Backed Storage >> [1256701.422339] gadget: high-speed config #1: Linux File-Backed Storage >> [1256934.915697] usb 3-1: reset high-speed USB device number 5 using dummy_hcd >> [1256934.951628] gadget: high-speed config #1: Linux File-Backed Storage >> [1256935.915155] usb 3-1: reset high-speed USB device number 5 using dummy_hcd >> [1256935.951090] gadget: high-speed config #1: Linux File-Backed Storage >> [1256936.095018] gadget: high-speed config #1: Linux File-Backed Storage >> [1317073.396892] usb-storage 3-1:1.0: Quirks match for vid 0525 pid a4a5: 10000 >> [1317073.396995] scsi53 : usb-storage 3-1:1.0 >> [1317074.411883] scsi 53:0:0:0: Direct-Access Linux File-CD >> Gadget 0302 PQ: 0 ANSI: 2 >> [1317074.412669] sd 53:0:0:0: Attached scsi generic sg3 type 0 >> [1317074.431910] sd 53:0:0:0: [sdc] 8388608 512-byte logical blocks: >> (4.29 GB/4.00 GiB) >> [1317074.443816] sd 53:0:0:0: [sdc] Write Protect is off >> [1317074.443821] sd 53:0:0:0: [sdc] Mode Sense: 0f 00 00 00 >> [1317074.455839] sd 53:0:0:0: [sdc] Write cache: enabled, read cache: >> enabled, doesn't support DPO or FUA >> [1317074.551757] sdc: sdc1 >> [1317074.683704] sd 53:0:0:0: [sdc] Attached SCSI removable disk >> ------------------------------ >> >> The problem is that IO performance is very poor. Writing 200Mb file >> takes quite a while: >> >> ------------------------------ >> $ ls -lh file >> -rw-rw-r-- 1 root del 206M Sep 4 09:34 file >> $ time sudo cp file /mnt/tmp/ >> real 11m59.618s >> user 0m0.000s >> sys 0m0.260s >> ------------------------------ >> >> >> Which is about 300K/sec. However the same file on the same system is >> copied to a real USB flash in less than a minute. Looks like it is >> emulating a USB 1.1 controller, not USB 2.0... >> >> iotop shows something like this: >> >> ------------------------------ >> TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND >> 9986 be/4 root 0.00 B/s 262.05 K/s 0.00 % 99.86 % cp file /mnt/tmp/ >> 20651 be/4 root 51.77 K/s 238.95 K/s 0.00 % 93.23 % [file-storage] >> ------------------------------ >> >> Can anything be done to improve the performance of >> g_mass_storage-emulated USB drive? >> >> PS: I am using kernel >> >> ------------------------------ >> $ uname -rm >> 3.2.0-4-686-pae i686 >> ------------------------------ >> >> Thanks in advance. > > This has nothing to do with g_mass_storage. > > What you are seeing is low performance of dummy-hcd. dummy-hcd depends > strongly on the timer setting; it won't really work properly unless you > have CONFIG_HZ set to 1000. In general, the performance of dummy-hcd > doesn't matter because it is meant only for testing. > > If you use g_mass_storage with a real USB device controller, you should > find that it performs much better. > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
