The first two address the performance regression noticed by Howard Spoelstra. The last two are just something I noticed at the same time. r~ Richard Henderson (4): target/ppc: Use probe_access for LSW, STSW target/ppc: Use probe_access for LMW, STMW target/ppc: Remove redundant mask in DCBZ target/ppc: Use probe_write for DCBZ target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- 1 file changed, 162 insertions(+), 35 deletions(-) -- 2.20.1
00:51 Čet, 30.01.2020. Richard Henderson <richard.henderson@linaro.org> је написао/ла: > > The first two address the performance regression noticed > by Howard Spoelstra. The last two are just something I > noticed at the same time. > But, performance regression, according to Howard bisect analysis, happened because of the change in target-independant code, and the fix presented here is in target-specific code. This defies basic logic and deserves clear and detailed explanation. My additional concern, of course, is: Are other targets exposed to performance degradation, and why? Thanks, Aleksandar > > r~ > > > Richard Henderson (4): > target/ppc: Use probe_access for LSW, STSW > target/ppc: Use probe_access for LMW, STMW > target/ppc: Remove redundant mask in DCBZ > target/ppc: Use probe_write for DCBZ > > target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- > 1 file changed, 162 insertions(+), 35 deletions(-) > > -- > 2.20.1 > >
On 1/29/20 5:35 PM, Aleksandar Markovic wrote: > 00:51 Čet, 30.01.2020. Richard Henderson <richard.henderson@linaro.org > <mailto:richard.henderson@linaro.org>> је написао/ла: >> >> The first two address the performance regression noticed >> by Howard Spoelstra. The last two are just something I >> noticed at the same time. >> > > But, performance regression, according to Howard bisect analysis, happened > because of the change in target-independant code, and the fix presented here is > in target-specific code. This defies basic logic and deserves clear and > detailed explanation. > > My additional concern, of course, is: Are other targets exposed to performance > degradation, and why? Potentially, yes. However: It requires lots of loads in a loop, on a hot path. I would not have guessed that the ppc32 Load Multiple Word (et al) was on a hot path at all, since the instructions are deprecated. But that's what an ancient os gets you, I suppose. r~
On Thu, Jan 30, 2020 at 5:09 PM Richard Henderson <richard.henderson@linaro.org> wrote: > > On 1/29/20 5:35 PM, Aleksandar Markovic wrote: > > My additional concern, of course, is: Are other targets exposed to performance > > degradation, and why? > > Potentially, yes. However: > > It requires lots of loads in a loop, on a hot path. I would not have guessed > that the ppc32 Load Multiple Word (et al) was on a hot path at all, since the > instructions are deprecated. But that's what an ancient os gets you, I suppose. > OK. > > r~
On Thu, Jan 30, 2020 at 12:50 AM Richard Henderson < richard.henderson@linaro.org> wrote: > The first two address the performance regression noticed > by Howard Spoelstra. The last two are just something I > noticed at the same time. > > > r~ > > > Richard Henderson (4): > target/ppc: Use probe_access for LSW, STSW > target/ppc: Use probe_access for LMW, STMW > target/ppc: Remove redundant mask in DCBZ > target/ppc: Use probe_write for DCBZ > > target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- > 1 file changed, 162 insertions(+), 35 deletions(-) > > -- > 2.20.1 > > Hi, I can confirm these patches fix the performance issue I reported. Thanks, Howard
On Wed, Jan 29, 2020 at 03:50:36PM -0800, Richard Henderson wrote: > The first two address the performance regression noticed > by Howard Spoelstra. The last two are just something I > noticed at the same time. Applied to ppc-for-5.0, thanks. > > > r~ > > > Richard Henderson (4): > target/ppc: Use probe_access for LSW, STSW > target/ppc: Use probe_access for LMW, STMW > target/ppc: Remove redundant mask in DCBZ > target/ppc: Use probe_write for DCBZ > > target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- > 1 file changed, 162 insertions(+), 35 deletions(-) > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
As this patch set solved the performance issue and even led to the highest scores I ever saw on the benchmark tool I used, let me add a: Tested-by: Howard Spoelstra <hsp.cat7@gmail.com> On Thu, Jan 30, 2020 at 12:50 AM Richard Henderson < richard.henderson@linaro.org> wrote: > The first two address the performance regression noticed > by Howard Spoelstra. The last two are just something I > noticed at the same time. > > > r~ > > > Richard Henderson (4): > target/ppc: Use probe_access for LSW, STSW > target/ppc: Use probe_access for LMW, STMW > target/ppc: Remove redundant mask in DCBZ > target/ppc: Use probe_write for DCBZ > > target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- > 1 file changed, 162 insertions(+), 35 deletions(-) > > -- > 2.20.1 > >
On Thu, Jan 30, 2020 at 4:09 PM Howard Spoelstra <hsp.cat7@gmail.com> wrote: > > As this patch set solved the performance issue and even led to the highest scores I ever saw on the benchmark tool I used, let me add a: > This makes my question to Richard more important: Are other targets exposed to performance degradation, and why? > Tested-by: Howard Spoelstra <hsp.cat7@gmail.com> > > On Thu, Jan 30, 2020 at 12:50 AM Richard Henderson <richard.henderson@linaro.org> wrote: >> >> The first two address the performance regression noticed >> by Howard Spoelstra. The last two are just something I >> noticed at the same time. >> >> >> r~ >> >> >> Richard Henderson (4): >> target/ppc: Use probe_access for LSW, STSW >> target/ppc: Use probe_access for LMW, STMW >> target/ppc: Remove redundant mask in DCBZ >> target/ppc: Use probe_write for DCBZ >> >> target/ppc/mem_helper.c | 197 +++++++++++++++++++++++++++++++++------- >> 1 file changed, 162 insertions(+), 35 deletions(-) >> >> -- >> 2.20.1 >>
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