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Date: Tue, 7 Jun 2011 10:49:12 +0300 From: Lucian Adrian Grijincu <lucian.grijincu@...il.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net> Subject: Re: [PATCH 2/2] net: dummy: allocate devices with alloc_netdev_id On Tue, Jun 7, 2011 at 6:19 AM, Eric Dumazet <eric.dumazet@...il.com> wrote: > Le mardi 07 juin 2011 à 04:39 +0300, Lucian Adrian Grijincu a écrit : >> The most like case is that no one else is registering devices with a >> name like "dummy%d". >> >> We can bring the complexity down by replacing: >> - alloc_netdev_id which is O(N) with >> - alloc_netdev_id which, on the average case, is O(1). >> >> $ time modprobe dummy numdummies=5000 >> - with alloc_netdev : 9.50s >> - with alloc_netdev_id: 3.50s >> >> NOTE: Stats generated on a heavily patched 3.0-rc1 which replaces the >> current O(N^2) sysctl algorithm with a better one. > > Yes, and disabled hotplug I guess. $ cat .config | grep HOTPLUG CONFIG_HOTPLUG=y # CONFIG_MEMORY_HOTPLUG is not set CONFIG_HOTPLUG_CPU=y CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG=y CONFIG_ACPI_HOTPLUG_CPU=y # CONFIG_HOTPLUG_PCI is not set I would guess you're going for CONFIG_HOTPLUG_PCI or CONFIG_HOTPLUG_CPU, but I don't understand the implications. > Dont try this on a random computer ;) Could you briefly explain what's at stake here? What can go wrong if we do this? I wasn't advocating replacing all alloc_netdev calls with the new call. > # time modprobe dummy numdummies=5000 > > real 4m45.646s > user 0m0.000s > sys 0m12.440s > # uptime > 05:13:46 up 13:30, 3 users, load average: 11221.41, 6918.70, 3101.12 > # uptime > 05:18:45 up 13:35, 3 users, load average: 12159.82, 10277.39, 5623.19 I don't get where you're going with these stats. I don't care much about these patches, and even less if they're fundamentally borked, but I'd like to know how/why they're not ok. Please spare a second and illuminate me; I feel left out on a big joke. -- . ..: Lucian -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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