linux-kernel - Re: loaded router, excessive getnstimeofday in oprofile

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <48B70AAA.7010504@hp.com>
Date:	Thu, 28 Aug 2008 13:29:30 -0700
From:	Rick Jones <rick.jones2@...com>
To:	David Miller <davem@...emloft.net>
CC:	jmalicki@...acarta.com, andi@...stfloor.org, johnpol@....mipt.ru,
	dada1@...mosbay.com, denys@...p.net.lb, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, juhlenko@...mai.com, sammy@...my.net
Subject: Re: loaded router, excessive getnstimeofday in oprofile

> 
> The issue is the ordering of processing the requests.
> 
> So if request A arrived on interface 1 before request B arrived on
> interface 2, the trade described in A should be performed before the
> one in B.
> 
> This is not "arcance" as you seem to suppose it might be, but rather
> pretty clear fair handling or requests sent between trading desks.

Has the request "hit the trading system" when it hits the NIC, or when 
it hits the application executing the trade?  If the SEC calls for when 
it hits the NIC, then none of what is done today is really 
accurate/correct and one would need to start using NIC HW timestamps, 
synchronized with the host and the other NICs in the system no?

The way things are today, there really isn't much guarantee that hitting 
NIC 1 before NIC 2 will result in a driver-generated timestamp for the 
NIC 1 packet which is before the driver-generated timestamp for the NIC 
2 packet.  It will be luck of the interrupt coalescing interaction with 
other traffic on the NIC and/or polling out of NAPI right?

rick jones
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/