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Date: Sat, 19 Jul 2008 05:51:44 +0100 From: Simon Arlott <simon@...e.lp0.eu> To: Arjan van de Ven <arjan@...radead.org> CC: linux-kernel@...r.kernel.org, mingo@...e.hu, dwalker@...sta.com Subject: Re: [patch 0/3] fastboot patches series 1 On 18/07/08 23:15, Arjan van de Ven wrote: > Hi, > > this 3 patch series introduces the concept of "asynchronous initcalls". > This is a new initcall level (6a) that has the following semantics: > 1) Level 6a gets run asynchronously from the regular "driver" initcalls > 2) Level 6a starts after level 5 (fs_initcall). > 3) Within the 6a category, the initcalls are processed sequentially; > there is no parallelism between them. The parallelism is more > like a bottom halve than it is like a softirq this way. > This is a nice property since it leads to predictable device ordering > while being able to move various pieces out of the critical boot path > 4) The kernel will synchronize at the end of all initcalls to insure > that we don't free initmem until all this is done (trust me, we need > this) > > With these 3 patches I managed to shave off 0.4 seconds off my kernel > boot (this may sound little, but it's a reduction from 1.9 seconds to a > little under 1.5 seconds, which is significant both compared to the > kernel boot time as well as the full distro boot time on this box) This is a great idea... I was thinking about trying to run usb initialisation in parallel because it takes so long. It would be more useful to run usb init in parallel with ide/sata on my system, since they both take a while to run (I realise /dev/sd* will be in a unstable order). Unfortunately this patch set has the opposite effect on my system... something appears to be going badly wrong (logs attached). The mouse pointer was really erratic so I reconnected it (by turning the hub in my display off/on)... that took a while: [ 207.898357] usb 1-1: device not accepting address 13, error -110 [ 223.534045] usb 1-1: device not accepting address 14, error -110 [ 234.058288] usb 1-1: device not accepting address 15, error -110 [ 244.582171] usb 1-1: device not accepting address 16, error -110 Strangely, when this output appeared: [ 1.370693] ehci_hcd 0000:00:02.1: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004 I didn't see anything else until the next screenful of output, but the log shows this output before that: [ 4.683674] usb usb1: default language 0x0409 [ 7.548621] usb usb1: uevent There was another long pause with no output but I can't see where from reading back the log. The timestamps are a bit confused too, jumping +/-10s. $ lsusb -t Bus# 2 `-Dev# 1 Vendor 0x1d6b Product 0x0001 `-Dev# 2 Vendor 0x04f9 Product 0x0027 Bus# 1 `-Dev# 1 Vendor 0x1d6b Product 0x0002 `-Dev# 17 Vendor 0x0424 Product 0x2512 |-Dev# 18 Vendor 0x0424 Product 0x2602 | |-Dev# 20 Vendor 0x0424 Product 0x2228 | `-Dev# 21 Vendor 0x046d Product 0xc044 `-Dev# 19 Vendor 0x046d Product 0x08ce -- Simon Arlott View attachment "dmesg-after-fastboot" of type "text/plain" (162211 bytes) View attachment "dmesg-before-fastboot" of type "text/plain" (108382 bytes) View attachment ".config" of type "text/plain" (60209 bytes)
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