Messages in this thread | | | From | <> | Subject | Re: [PATCH] mtd: revert "spi-nor: intel: provide a range for poll_timout" | Date | Wed, 22 Jul 2020 17:03:32 +0000 |
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Hi, Alexander,
On 7/22/20 7:37 PM, Alexander Sverdlin wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > Hello Luis, > > thank you for the patch! > > On 11/06/2020 00:46, Luis Alberto Herrera wrote: >> This change reverts aba3a882a178: "mtd: spi-nor: intel: provide a range >> for poll_timout". That change introduces a performance regression when >> reading sequentially from flash. Logging calls to intel_spi_read without >> this change we get: >> >> Start MTD read >> [ 20.045527] intel_spi_read(from=1800000, len=400000) >> [ 20.045527] intel_spi_read(from=1800000, len=400000) >> [ 282.199274] intel_spi_read(from=1c00000, len=400000) >> [ 282.199274] intel_spi_read(from=1c00000, len=400000) >> [ 544.351528] intel_spi_read(from=2000000, len=400000) >> [ 544.351528] intel_spi_read(from=2000000, len=400000) >> End MTD read >> >> With this change: >> >> Start MTD read >> [ 21.942922] intel_spi_read(from=1c00000, len=400000) >> [ 21.942922] intel_spi_read(from=1c00000, len=400000) >> [ 23.784058] intel_spi_read(from=2000000, len=400000) >> [ 23.784058] intel_spi_read(from=2000000, len=400000) >> [ 25.625006] intel_spi_read(from=2400000, len=400000) >> [ 25.625006] intel_spi_read(from=2400000, len=400000) >> End MTD read > > I've performed my testing as well and got the following results: > > Vanilla Linux 4.9 (i.e. before the introduction of the offending > patch): > > dd if=/dev/flash/by-name/XXX of=/dev/null bs=4k > 1280+0 records in > 1280+0 records out > 5242880 bytes (5.2 MB, 5.0 MiB) copied, 3.91981 s, 1.3 MB/s > > Vanilla 4.19 (i.e. with offending patch): > > dd if=/dev/flash/by-name/XXX of=/dev/null bs=4k > 1280+0 records in > 1280+0 records out > 5242880 bytes (5.2 MB, 5.0 MiB) copied, 6.70891 s, 781 kB/s > > 4.19 + revert: > > dd if=/dev/flash/by-name/XXX of=/dev/null bs=4k > 1280+0 records in > 1280+0 records out > 5242880 bytes (5.2 MB, 5.0 MiB) copied, 3.90503 s, 1.3 MB/s > > Therefore it looks good from my PoV: > > Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com> > >> Signed-off-by: Luis Alberto Herrera <luisalberto@google.com> >> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> >> --- >> drivers/mtd/spi-nor/controllers/intel-spi.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/mtd/spi-nor/controllers/intel-spi.c b/drivers/mtd/spi-nor/controllers/intel-spi.c >> index 61d2a0ad2131..2b89361a0d3a 100644 >> --- a/drivers/mtd/spi-nor/controllers/intel-spi.c >> +++ b/drivers/mtd/spi-nor/controllers/intel-spi.c >> @@ -292,7 +292,7 @@ static int intel_spi_wait_hw_busy(struct intel_spi *ispi) >> u32 val; >> >> return readl_poll_timeout(ispi->base + HSFSTS_CTL, val, >> - !(val & HSFSTS_CTL_SCIP), 40,>> + !(val & HSFSTS_CTL_SCIP), 0,
would you put 10 us here >> INTEL_SPI_TIMEOUT * 1000); >> } >> >> @@ -301,7 +301,7 @@ static int intel_spi_wait_sw_busy(struct intel_spi *ispi) >> u32 val; >> >> return readl_poll_timeout(ispi->sregs + SSFSTS_CTL, val, >> - !(val & SSFSTS_CTL_SCIP), 40, >> + !(val & SSFSTS_CTL_SCIP), 0,
also here, and re-do a test? I'm curios if the performance will be as it was before.
Thanks!
>> INTEL_SPI_TIMEOUT * 1000); >> } >> >> > > -- > Best regards, > Alexander Sverdlin. >
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