Date: Fri, 19 Nov 2004 12:02:07 +0900 From: Shunsuke SHINOMIYA <shino@fornext.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-stable@freebsd.org Subject: Re[2]: serious networking (em) performance (ggate and NFS) problem Message-ID: <20041119114233.C43B.SHINO@fornext.org> In-Reply-To: <200411182131.iAILVJ1T032003@apollo.backplane.com> References: <20041118124902.GC75559@freebie.xs4all.nl> <200411182131.iAILVJ1T032003@apollo.backplane.com>
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Hi list,
if you suppose your computer has sufficient performance, please try to
disable or adjust parameters of Interrupt Moderation of em.
In my router(Xeon 2.4GHz and on-board two em interfaces) case, it
improves a router's packet forwarding performance. I think the
interrupt delay by Interrupt Moderation caused NIF's input buffer
overflow or output buffer underrun in this case.
In order to disable Interrupt Moderation, modify src/sys/dev/em/if_em.c
like the following patch and set hw.em.{rx,tx}_{,abs_}int_delay zero by
sysctl.
*** if_em.c-1.44.2.3.orig Fri Nov 19 11:22:48 2004
--- if_em.c Fri Nov 19 11:23:39 2004
*************** em_initialize_receive_unit(struct adapte
*** 2611,2618 ****
--- 2611,2622 ----
/* Set the interrupt throttling rate. Value is calculated
* as DEFAULT_ITR = 1/(MAX_INTS_PER_SEC * 256ns) */
+ #if 1
+ #define DEFAULT_ITR 0
+ #else
#define MAX_INTS_PER_SEC 8000
#define DEFAULT_ITR 1000000000/(MAX_INTS_PER_SEC * 256)
+ #endif
E1000_WRITE_REG(&adapter->hw, ITR, DEFAULT_ITR);
}
--
Shunsuke SHINOMIYA <shino@fornext.org>
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