Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Friday 13 March 2009 16:23:15 Kumar Gala wrote: [...] This errata impacts a number of cores and so we should make this a CPU feature fixup rather than #ifdef code. It should impact only MPC5121e and probably MPC5123, but according to Freescale no other processors that use this core... Not sure about that.. But the errata impacts all e300c2/c3/c4 parts. Can someone please check if this is true? There should be errata's for all other parts that use one of these cores then. Anyway, I'll try to investigate about how to write a CPU feature fixup, I've never done that before (If you could give me a hint?) I've posted a patch that should add the CPU feature support. This is only compile tested. You'll need to try it out on real HW :) That's a problem right now: The only useable kernel for the MPC5121e is the one on the 'ads5121' head from denx, and that is version 2.6.24.6. Your patch (v3) does not apply to that kernel, so I would have to change a few things before I can actually try it out: #define CPU_FTR_NEED_DTLB_SW_LRU ASM_CONST(0x0001) In 2.6.24.6 this constant is used for something else. Would it be possible to pick anotherone, in order to make dual-kernel patches easier to maintain for now? + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ Why not use a bit vector since we only need one bit of information. Additionally we can use a single SPRG at that point instead to keep track of the LRU information. Sounds interesting. I am just learning my first steps in powerpc- assembly, so please forgive if this is a little inefficient still. I'll try again next week. Not at all. This has been on my todo list just not high priority so I'm happy to get someone to work on it and have setup already that can show perf differences. On your Todo list? Does that mean you know about another processor that has the same problem? I might work up a newer version w/the SPRG idea if I'm feeling up to it. Do you mean it is possible to just pick an SPRG that will be used only by this handler and make sure no other piece of software will touch it? Would be great. Is there a way of knowing which SPRG's are used by linux? I read in the e300 core-RM, that SPRG4...7 are unique to this iteration of the G2 anyway, so one of those might be a good candidate? I have quite a lot of work pressure right now, and unfortunately very little time I can dedicate to this. Given the fact that I also cannot test patches for mainline, because MPC5121e support is just not complete enough yet, do you agree if I modify my own patch (with ifdef's instead of CPU_FTR...) to give you feedback on performance impacts, while you implement it as CPU_FTR afterwards for mainline? That way I can avoid doing double work, and spend more time on testing it actually If you agree, I'll start hacking away on the SPRG version immediately :-) Best regards, -- David Jander Protonic Holland. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Mar 16, 2009, at 5:44 AM, David Jander wrote: On Friday 13 March 2009 16:23:15 Kumar Gala wrote: [...] This errata impacts a number of cores and so we should make this a CPU feature fixup rather than #ifdef code. It should impact only MPC5121e and probably MPC5123, but according to Freescale no other processors that use this core... Not sure about that.. But the errata impacts all e300c2/c3/c4 parts. Can someone please check if this is true? There should be errata's for all other parts that use one of these cores then. Anyway, I'll try to investigate about how to write a CPU feature fixup, I've never done that before (If you could give me a hint?) I've posted a patch that should add the CPU feature support. This is only compile tested. You'll need to try it out on real HW :) That's a problem right now: The only useable kernel for the MPC5121e is the one on the 'ads5121' head from denx, and that is version 2.6.24.6. Your patch (v3) does not apply to that kernel, so I would have to change a few things before I can actually try it out: #define CPU_FTR_NEED_DTLB_SW_LRU ASM_CONST(0x0001) In 2.6.24.6 this constant is used for something else. Would it be possible to pick anotherone, in order to make dual-kernel patches easier to maintain for now? + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ Why not use a bit vector since we only need one bit of information. Additionally we can use a single SPRG at that point instead to keep track of the LRU information. Sounds interesting. I am just learning my first steps in powerpc- assembly, so please forgive if this is a little inefficient still. I'll try again next week. Not at all. This has been on my todo list just not high priority so I'm happy to get someone to work on it and have setup already that can show perf differences. On your Todo list? Does that mean you know about another processor that has the same problem? Yes, I work at Freescale and am aware that the errata impacts all c2/ c3/c4 class chips. I might work up a newer version w/the SPRG idea if I'm feeling up to it. Do you mean it is possible to just pick an SPRG that will be used only by this handler and make sure no other piece of software will touch it? Would be great. Is there a way of knowing which SPRG's are used by linux? I read in the e300 core-RM, that SPRG4...7 are unique to this iteration of the G2 anyway, so one of those might be a good candidate? I was thinking one from SPRG4..7 should be fine since Linux doesn't use them for anything. We should try this w/SPRG w/memory to see if we notice any perf difference. I have quite a lot of work pressure right now, and unfortunately very little time I can dedicate to this. Given the fact that I also cannot test patches for mainline, because MPC5121e support is just not complete enough yet, do you agree if I modify my own patch (with ifdef's instead of CPU_FTR...) to give you feedback on performance impacts, while you implement it as CPU_FTR afterwards for mainline? That way I can avoid doing double work, and spend more time on testing it actually If you agree, I'll start hacking away on the SPRG version immediately :-) I think that's fine. The CPU feature bit is minor to deal with and Ben has stated he wants it to be a MMU feature which is something new as well. It should be easy to convert the CPU_FTR wrapping into #ifdefs instead. I have a few other patches related to this that I am not sure if they will apply to the 2.6.24.6 tree you are based on. - k ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
Forgot to mention: The patch is based on denx git tree head 'ads5121', but it should apply without problem (some offset at most) to mainline. Best regards, -- David Jander Protonic Holland. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
What does cat /proc/cpuinfo show on this board? +#ifdef CONFIG_PPC_MPC512x +/* MPC512x: workaround for errata in die M36P and earlier: + * Implement LRW for TLB way. + */ This errata impacts a number of cores and so we should make this a CPU feature fixup rather than #ifdef code. + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ Why not use a bit vector since we only need one bit of information. Additionally we can use a single SPRG at that point instead to keep track of the LRU information. + beq-0,113f /* Then goto 113: */ + + mfspr r1,SPRN_SRR1 + rlwinm r1,r1,0,15,13 /* Mask out SRR1[WAY] */ + mtspr SPRN_SRR1,r1 + + li r0,0 + stwxr0,r3,r2 /* Make lrw[] entry 0 */ + b 114f +113: + li r0,1 + stwxr0,r3,r2 /* Make lrw[] entry 1 */ +114: +#endif mfctr r0 /* Get PTE (linux-style) and check access */ mfspr r3,SPRN_DMISS @@ -688,6 +717,34 @@ DataStoreTLBMiss: .globl mol_trampoline .set mol_trampoline, i0x2f00 +#ifdef CONFIG_PPC_MPC512x +TlbWo: +/* MPC512x: workaround for errata in die M36P and earlier: + * Implement LRW for TLB way. + */ + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ + beq-0,113f /* Then goto 113: */ + + mfspr r1,SPRN_SRR1 + rlwinm r1,r1,0,15,13 /* Mask out SRR1[WAY] */ + mtspr SPRN_SRR1,r1 + + li r0,0 + stwxr0,r3,r2 /* Make lrw[] entry 0 */ + b 114f +113: + li r0,1 + stwxr0,r3,r2 /* Make lrw[] entry 1 */ +114: + b RFTlbWo +#endif + . = 0x3000 AltiVecUnavailable: @@ -1321,6 +1378,14 @@ intercept_table: .long 0, 0, 0, 0, 0, 0, 0, 0 .long 0, 0, 0, 0, 0, 0, 0, 0 .long 0, 0, 0, 0, 0, 0, 0, 0 + +#ifdef CONFIG_PPC_MPC512x +lrw: + .long 0, 0, 0, 0, 0, 0, 0, 0 + .long 0, 0, 0, 0, 0, 0, 0, 0 + .long 0, 0, 0, 0, 0, 0, 0, 0 + .long 0, 0, 0, 0, 0, 0, 0, 0 +#endif /* Room for two PTE pointers, usually the kernel and current user pointers * to their respective root page table. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Mar 13, 2009, at 5:26 AM, David Jander wrote: Forgot to mention: The patch is based on denx git tree head 'ads5121', but it should apply without problem (some offset at most) to mainline. Best regards, Out of interest did this version produce better performance on the benchmarks than your v1 version? - k ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Friday 13 March 2009 14:22:22 Kumar Gala wrote: On Mar 13, 2009, at 5:26 AM, David Jander wrote: Forgot to mention: The patch is based on denx git tree head 'ads5121', but it should apply without problem (some offset at most) to mainline. Best regards, Out of interest did this version produce better performance on the benchmarks than your v1 version? Some examples: 1.- mplayer -nosound -benchmark testfile.mpeg (a DVD-mpeg2 file): No fix at all: VC: 30.5s VO: 53.4s Sys:1.95s Total: 85.8s First fix (force writes to way 0): VC: 24.3s VO: 40.6s Sys:1.95s Total: 66.9s Complete fix (implementing lrw): VC: 23.1s VO: 31.5s Sys:1.03s Total: 55.6s 2.- prboom -timedemo doombench1 (where doombench1.lmp is prerecorded demo): No fix at all: 14.1 fps First fix (force writes to way 0): 16.7 fps Complete fix (implementing lrw): 18.1 fps 3.- Synthetic and pathologic memcpy() benchmark: No fix at all: 26 Mbyte/s First fix (force writes to way 0): 160 MByte/s Complete fix (implementing lrw): 163 MByte/s Note, that this benchmark should't really show any difference between v1 and v2, since v1 is almost the best possible fix for copy's only. Tell me if you know of some other interesting benchmarks to try. Best regards, -- David Jander Protonic Holland. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Friday 13 March 2009 14:21:57 Kumar Gala wrote: What does cat /proc/cpuinfo show on this board? # cat /proc/cpuinfo processor : 0 cpu : e300c4 clock : 400.00MHz revision: 1.0 (pvr 8086 2010) bogomips: 99.84 timebase: 5000 platform: MPC5121 Generic +#ifdef CONFIG_PPC_MPC512x +/* MPC512x: workaround for errata in die M36P and earlier: + * Implement LRW for TLB way. + */ This errata impacts a number of cores and so we should make this a CPU feature fixup rather than #ifdef code. It should impact only MPC5121e and probably MPC5123, but according to Freescale no other processors that use this core... Anyway, I'll try to investigate about how to write a CPU feature fixup, I've never done that before (If you could give me a hint?) + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ Why not use a bit vector since we only need one bit of information. Additionally we can use a single SPRG at that point instead to keep track of the LRU information. Sounds interesting. I am just learning my first steps in powerpc-assembly, so please forgive if this is a little inefficient still. I'll try again next week. Greetings, -- David Jander Protonic Holland. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [RFC] [PATCH v2] MPC5121 TLB errata workaround
On Mar 13, 2009, at 9:24 AM, David Jander wrote: On Friday 13 March 2009 14:21:57 Kumar Gala wrote: What does cat /proc/cpuinfo show on this board? # cat /proc/cpuinfo processor : 0 cpu : e300c4 clock : 400.00MHz revision: 1.0 (pvr 8086 2010) bogomips: 99.84 timebase: 5000 platform: MPC5121 Generic +#ifdef CONFIG_PPC_MPC512x +/* MPC512x: workaround for errata in die M36P and earlier: + * Implement LRW for TLB way. + */ This errata impacts a number of cores and so we should make this a CPU feature fixup rather than #ifdef code. It should impact only MPC5121e and probably MPC5123, but according to Freescale no other processors that use this core... Not sure about that.. But the errata impacts all e300c2/c3/c4 parts. Anyway, I'll try to investigate about how to write a CPU feature fixup, I've never done that before (If you could give me a hint?) I've posted a patch that should add the CPU feature support. This is only compile tested. You'll need to try it out on real HW :) + mfspr r3,SPRN_DMISS + rlwinm r3,r3,19,25,29 /* Get Address bits 19:15 */ + lis r2,l...@ha /* Search index in lrw[] */ + addir2,r2,l...@l + tophys(r2,r2) + lwzxr1,r3,r2 /* Get item from lrw[] */ + cmpwi 0,r1,0 /* Was it way 0 last time? */ Why not use a bit vector since we only need one bit of information. Additionally we can use a single SPRG at that point instead to keep track of the LRU information. Sounds interesting. I am just learning my first steps in powerpc- assembly, so please forgive if this is a little inefficient still. I'll try again next week. Not at all. This has been on my todo list just not high priority so I'm happy to get someone to work on it and have setup already that can show perf differences. I might work up a newer version w/the SPRG idea if I'm feeling up to it. - k ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
