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| author | Siddhesh Poyarekar <siddhesh@redhat.com> | 2013-06-12 10:36:48 +0530 |
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| committer | Siddhesh Poyarekar <siddhesh@redhat.com> | 2013-06-12 10:36:48 +0530 |
| commit | 2506109403de69bd454de27835d42e6eb6ec3abc (patch) | |
| tree | f6830d3dba0fff9d4b5909616c0a111599263a8d /ChangeLog | |
| parent | 59b3055595783f347b899a9588ddad0280feded9 (diff) | |
| download | glibc-2506109403de69bd454de27835d42e6eb6ec3abc.tar.gz glibc-2506109403de69bd454de27835d42e6eb6ec3abc.tar.xz glibc-2506109403de69bd454de27835d42e6eb6ec3abc.zip | |
Set/restore rounding mode only when needed
The most common use case of math functions is with default rounding mode, i.e. rounding to nearest. Setting and restoring rounding mode is an unnecessary overhead for this, so I've added support for a context, which does the set/restore only if the FP status needs a change. The code is written such that only x86 uses these. Other architectures should be unaffected by it, but would definitely benefit if the set/restore has as much overhead relative to the rest of the code, as the x86 bits do. Here's a summary of the performance improvement due to these improvements; I've only mentioned functions that use the set/restore and have benchmark inputs for x86_64: Before: cos(): ITERS:4.69335e+08: TOTAL:28884.6Mcy, MAX:4080.28cy, MIN:57.562cy, 16248.6 calls/Mcy exp(): ITERS:4.47604e+08: TOTAL:28796.2Mcy, MAX:207.721cy, MIN:62.385cy, 15543.9 calls/Mcy pow(): ITERS:1.63485e+08: TOTAL:28879.9Mcy, MAX:362.255cy, MIN:172.469cy, 5660.86 calls/Mcy sin(): ITERS:3.89578e+08: TOTAL:28900Mcy, MAX:704.859cy, MIN:47.583cy, 13480.2 calls/Mcy tan(): ITERS:7.0971e+07: TOTAL:28902.2Mcy, MAX:1357.79cy, MIN:388.58cy, 2455.55 calls/Mcy After: cos(): ITERS:6.0014e+08: TOTAL:28875.9Mcy, MAX:364.283cy, MIN:45.716cy, 20783.4 calls/Mcy exp(): ITERS:5.48578e+08: TOTAL:28764.9Mcy, MAX:191.617cy, MIN:51.011cy, 19071.1 calls/Mcy pow(): ITERS:1.70013e+08: TOTAL:28873.6Mcy, MAX:689.522cy, MIN:163.989cy, 5888.18 calls/Mcy sin(): ITERS:4.64079e+08: TOTAL:28891.5Mcy, MAX:6959.3cy, MIN:36.189cy, 16062.8 calls/Mcy tan(): ITERS:7.2354e+07: TOTAL:28898.9Mcy, MAX:1295.57cy, MIN:380.698cy, 2503.7 calls/Mcy So the improvements are: cos: 27.9089% exp: 22.6919% pow: 4.01564% sin: 19.1585% tan: 1.96086% The downside of the change is that it will have an adverse performance impact on non-default rounding modes, but I think the tradeoff is justified.
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index f42d563fb8..66ac05a36b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,52 @@ +2013-06-12 Siddhesh Poyarekar <siddhesh@redhat.com> + + * include/fenv.h: Include stdbool.h. + (struct rm_ctx): New structure. + * sysdeps/generic/math_private.h (SET_RESTORE_ROUND_GENERIC): + Define macro. + (SET_RESTORE_ROUND): Define using SET_RESTORE_ROUND_GENERIC. + (SET_RESTORE_ROUNDF): Likewise. + (SET_RESTORE_ROUNDL): Likewise. + (SET_RESTORE_ROUND_NOEX): Likewise. + (SET_RESTORE_ROUND_NOEXF): Likewise. + (SET_RESTORE_ROUND_NOEXL): Likewise. + (SET_RESTORE_ROUND_53BIT): Likewise. + [HAVE_RM_CTX] (libc_feresetround_noex_ctx): Define macro. + (libc_feresetround_noexf_ctx): Likewise. + (libc_feresetround_noexl_ctx): Likewise. + (libc_feholdsetround_53bit_ctx): Likewise. + (libc_feresetround_53bit_ctx): Likewise. + * sysdeps/i386/fpu/fenv_private.h (HAVE_RM_CTX): Define macro. + (libc_feholdexcept_setround_sse_ctx): New function. + (libc_fesetenv_sse_ctx): Likewise. + (libc_feupdateenv_sse_ctx): Likewise. + (libc_feholdexcept_setround_387_prec_ctx): Likewise. + (libc_feholdexcept_setround_387_ctx): Likewise. + (libc_feholdexcept_setround_387_53bit_ctx): Likewise. + (libc_feholdsetround_387_prec_ctx): Likewise. + (libc_feholdsetround_387_ctx): Likewise. + (libc_feholdsetround_387_53bit_ctx): Likewise. + (libc_feholdsetround_sse_ctx): Likewise. + (libc_feresetround_sse_ctx): Likewise. + (libc_feresetround_387_ctx): Likewise. + (libc_feupdateenv_387_ctx): Likewise. + (libc_feholdexcept_setroundf_ctx): Define macro. + (libc_fesetenvf_ctx): Likewise. + (libc_feupdateenvf_ctx): Likewise. + (libc_feholdsetroundf_ctx): Likewise. + (libc_feresetroundf_ctx): Likewise. + (libc_feholdexcept_setround_ctx): Likewise. + (libc_fesetenv_ctx): Likewise. + (libc_feupdateenv_ctx): Likewise. + (libc_feholdsetround_ctx): Likewise. + (libc_feresetround_ctx): Likewise. + (libc_feholdexcept_setroundl_ctx): Likewise. + (libc_feupdateenvl_ctx): Likewise. + (libc_feholdsetroundl_ctx): Likewise. + (libc_feresetroundl_ctx): Likewise. + [!__SSE2_MATH__] (libc_feholdsetround_53bit_ctx): Likewise. + (libc_feresetround_53bit_ctx): Likewise. + 2013-06-11 Siddhesh Poyarekar <siddhesh@redhat.com> * locale/iso-639.def: Convert to UTF-8. |