On 22 June 2017 at 12:57, Will Newton <will.newton@xxxxxxxxx> wrote: > Reduce max_segs to 64, a value that allows allocation of an entire > EDMA descriptor list within a single page - EDMA descriptors > are 40 bytes and the header is much larger. This avoids doing a > higher order GFP_ATOMIC allocation in edma_prep_slave_sg > when setting up a transfer which can potentially fail due to > fragmentation under heavy I/O load. > > The current value of 1024 is unusually high in comparison to > other mmc host drivers which mostly use values of between 1 > and 256. The EDMA driver at present splits lists above 20 > segments in any case so reducing the size of lists we pass to > it shouldn't add much overhead. > > Signed-off-by: Will Newton <willn@xxxxxxxx> Thanks, applied for next! Kind regards Uffe > --- > drivers/mmc/host/omap_hsmmc.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > Changes in v2: > - More verbose commit message > - Rebased onto current master > > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c > index 8c39dcc..bbcca93 100644 > --- a/drivers/mmc/host/omap_hsmmc.c > +++ b/drivers/mmc/host/omap_hsmmc.c > @@ -2097,9 +2097,9 @@ static int omap_hsmmc_probe(struct platform_device *pdev) > host->dbclk = NULL; > } > > - /* Since we do only SG emulation, we can have as many segs > - * as we want. */ > - mmc->max_segs = 1024; > + /* Set this to a value that allows allocating an entire descriptor > + * list within a page (zero order allocation). */ > + mmc->max_segs = 64; > > mmc->max_blk_size = 512; /* Block Length at max can be 1024 */ > mmc->max_blk_count = 0xFFFF; /* No. of Blocks is 16 bits */ > -- > 2.9.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
