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2025-11-20lib: test_mul_u64_u64_div_u64(): test the 32bit code on 64bitDavid Laight
There are slight differences in the mul_u64_add_u64_div_u64() code between 32bit and 64bit systems. Compile and test the 32bit version on 64bit hosts for better test coverage. Link: https://lkml.kernel.org/r/20251105201035.64043-10-david.laight.linux@gmail.com Signed-off-by: David Laight <david.laight.linux@gmail.com> Reviewed-by: Nicolas Pitre <npitre@baylibre.com> Cc: Biju Das <biju.das.jz@bp.renesas.com> Cc: Borislav Betkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Li RongQing <lirongqing@baidu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20lib: test_mul_u64_u64_div_u64(): test both generic and arch versionsDavid Laight
Change the #if in div64.c so that test_mul_u64_u64_div_u64.c can compile and test the generic version (including the 'long multiply') on architectures (eg amd64) that define their own copy. Test the kernel version and the locally compiled version on all arch. Output the time taken (in ns) on the 'test completed' trace. For reference, on my zen 5, the optimised version takes ~220ns and the generic version ~3350ns. Using the native multiply saves ~200ns and adding back the ilog2() 'optimisation' test adds ~50ms. Link: https://lkml.kernel.org/r/20251105201035.64043-7-david.laight.linux@gmail.com Signed-off-by: David Laight <david.laight.linux@gmail.com> Reviewed-by: Nicolas Pitre <npitre@baylibre.com> Cc: Biju Das <biju.das.jz@bp.renesas.com> Cc: Borislav Betkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Li RongQing <lirongqing@baidu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20lib: add tests for mul_u64_u64_div_u64_roundup()David Laight
Replicate the existing mul_u64_u64_div_u64() test cases with round up. Update the shell script that verifies the table, remove the comment markers so that it can be directly pasted into a shell. Rename the divisor from 'c' to 'd' to match mul_u64_add_u64_div_u64(). It any tests fail then fail the module load with -EINVAL. Link: https://lkml.kernel.org/r/20251105201035.64043-6-david.laight.linux@gmail.com Signed-off-by: David Laight <david.laight.linux@gmail.com> Reviewed-by: Nicolas Pitre <npitre@baylibre.com> Cc: Biju Das <biju.das.jz@bp.renesas.com> Cc: Borislav Betkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Li RongQing <lirongqing@baidu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01mul_u64_u64_div_u64: basic sanity testNicolas Pitre
Verify that edge cases produce proper results, and some more. [npitre@baylibre.com: avoid undefined shift value] Link: https://lkml.kernel.org/r/7rrs9pn1-n266-3013-9q6n-1osp8r8s0rrn@syhkavp.arg Link: https://lkml.kernel.org/r/20240707190648.1982714-3-nico@fluxnic.net Signed-off-by: Nicolas Pitre <npitre@baylibre.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Cc: Biju Das <biju.das.jz@bp.renesas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>