Hello.
> Do not forget to substitute your RAM size in
>#define WRITE_ALLOCATE_LIMIT
Thanks to Alan Cox's hint - there is no need for manual tuning now.
Attached [new] version of patch (against 2.2.0pre7) should enable write
allocate for AMD K6 model 6/7 processors. On my system it gives 5-7%
increase in speed.
-- With best wishes, Alexey Vyskubov. This is a message. Or something silly like that.--_=XFMail.1.3.p0.Linux:990117193159:323=_ Content-Disposition: attachment; filename="k6-patch" Content-Description: k6-patch Content-Type: text/plain; charset=KOI8-R; name=k6-patch; SizeOnDisk=2216 Content-Transfer-Encoding: 7bit
--- linux/arch/i386/kernel/setup.c.was Sun Jan 17 12:17:11 1999 +++ linux/arch/i386/kernel/setup.c Sun Jan 17 19:13:26 1999 @@ -601,6 +601,31 @@ static char *cpu_vendor_names[] __initdata = { "Intel", "Cyrix", "AMD", "UMC", "NexGen", "Centaur" }; +#define AMD_WHCR 0xc0000082 /* AMD MSR WHCR */ + +int enable_write_allocate (int size) +{ + u32 ra, rd; + rd = 0; + + ra = size >> 2; /* EAX = 2*(RAM/4) */ + ra = (ra << 1) + 1; /* +1 for no memory hole at 15-16MB */ + + +#define walloc(msr, val1, val2) __asm__ __volatile__ (" pushf + cli + wbinvd + wrmsr + popf"\ + : /* no outputs */\ + : "c" (msr),\ + "a" (val1), "d" (val2)) + walloc(AMD_WHCR, ra, rd); + rdmsr(AMD_WHCR, ra, rd); /* Let's see what's happened */ + ra = ra & 0xfe; /* Drop last bit (memory hole) */ + ra = ra << 1; + return((int)ra); +} __initfunc(void print_cpu_info(struct cpuinfo_x86 *c)) { @@ -621,8 +646,54 @@ if (c->x86_mask || c->cpuid_level>=0) printk(" stepping %02x", c->x86_mask); - - if(c->x86_vendor == X86_VENDOR_CENTAUR) + + if ( (c->x86_vendor == X86_VENDOR_AMD) && + ((c->x86_model == 6) || (c->x86_model == 7))) + { + + u32 ra, rd; + u32 ram; + int mem; + + + printk("\nAMD K6 processor, model %d found.", c->x86_model); + printk("\nChecking write allocate state... "); + + ram = max_mapnr * (PAGE_SIZE >> 10); /* RAM size in Kb */ + ram = ram >> 10; /* RAM size in Mb */ + + rdmsr(AMD_WHCR, ra, rd); + mem = (ra & 0xfe) << 1; + + if (mem) { + printk("Write allocate is enabled for %d MB of memory", mem); + } else { + printk("Write allocate is disabled."); + } + + if (!(mem == ram)) { + printk("\nTrying to enable write alocate for %d MB of memory", ram); + mem = ram; + mem = enable_write_allocate(mem); + + if (!(mem == ram)) { + printk("\nFailed!!!"); + } + printk("\nWrite allocate is enabled for %d MB of memory", mem); + } + + rdmsr(AMD_WHCR, ra, rd); + + if (ra & 0x100) { + printk("\nWARNING: WCDE bit is 1."); + } + + if (!(ra & 0x1)) { + printk("\nWARNING: Memory hole at 15-16M is enabled."); + } + } + + if (c->x86_vendor == X86_VENDOR_CENTAUR) { u32 hv,lv; rdmsr(0x107, lv, hv);
--_=XFMail.1.3.p0.Linux:990117193159:323=_-- End of MIME message
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