Messages in this thread Patch in this message | | | Date | Thu, 13 Jun 2002 15:01:19 +1000 | From | Rusty Russell <> | Subject | Re: [PATCH] 2.5.21 Nonlinear CPU support |
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On Wed, 12 Jun 2002 02:26:41 -0700 (PDT) "David S. Miller" <davem@redhat.com> wrote:
> From: Rusty Russell <rusty@rustcorp.com.au> > Date: Wed, 12 Jun 2002 16:58:23 +1000 > > In message <20020611.021043.04190747.davem@redhat.com> you write: > > And remember, it's the anal "every microoptimization at all costs" > > people that keep the kernel sane and from running out of control bloat > > wise. > > But it also gave us crap like net/ipv4/route.c:ip_rt_acct_read() 8( > > That's far from being an attempt optimization :-)
I was giving you the benifit of the doubt, that both the design (binary data from /proc) and the code (#ifdef, cpu_logical_map(0), and "256" sprinkled everywhere) were some insane attempt at speed, rather that a demonstration of sheer programming idiocy.
I stand corrected 8). This papers over the damage:
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.21/net/ipv4/route.c working-2.5.21-ipacct/net/ipv4/route.c --- linux-2.5.21/net/ipv4/route.c Mon May 13 12:00:40 2002 +++ working-2.5.21-ipacct/net/ipv4/route.c Thu Jun 13 14:33:41 2002 @@ -2418,10 +2418,15 @@ #ifdef CONFIG_NET_CLS_ROUTE struct ip_rt_acct *ip_rt_acct; +/* This code sucks. But you should have seen it before! --RR */ + +/* IP route accounting ptr for this logical cpu number. */ +#define IP_RT_ACCT_CPU(i) (ip_rt_acct + cpu_logical_map(i) * 256) + static int ip_rt_acct_read(char *buffer, char **start, off_t offset, int length, int *eof, void *data) { - *start = buffer; + unsigned int i; if ((offset & 3) || (length & 3)) return -EIO; @@ -2430,35 +2435,18 @@ length = sizeof(struct ip_rt_acct) * 256 - offset; *eof = 1; } - if (length > 0) { - u32 *dst = (u32*)buffer; - u32 *src = (u32*)(((u8*)ip_rt_acct) + offset); - - memcpy(dst, src, length); - -#ifdef CONFIG_SMP - if (smp_num_cpus > 1 || cpu_logical_map(0) != 0) { - int i; - int cnt = length / 4; - - for (i = 0; i < smp_num_cpus; i++) { - int cpu = cpu_logical_map(i); - int k; - if (cpu == 0) - continue; - - src = (u32*)(((u8*)ip_rt_acct) + offset + - cpu * 256 * sizeof(struct ip_rt_acct)); + /* Copy first cpu. */ + *start = buffer; + memcpy(buffer, IP_RT_ACCT_CPU(0), length); - for (k = 0; k < cnt; k++) - dst[k] += src[k]; - } - } -#endif - return length; + /* Add the other cpus in, one int at a time */ + for (i = 1; i < smp_num_cpus; i++) { + unsigned int j; + for (j = 0; j < length/4; j++) + ((u32*)buffer)[j] += ((u32*)IP_RT_ACCT_CPU(i))[j]; } - return 0; + return length; } #endif -- there are those who do and those who hang on and you don't see too many doers quoting their contemporaries. -- Larry McVoy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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