From 642c28ab86f7666d2ac62a0dc391b4c3121f1d6e Mon Sep 17 00:00:00 2001 From: David Jander Date: Tue, 23 Jun 2015 11:43:52 +0200 Subject: [PATCH] mmc: core: Optimize case for exactly one erase-group budget In the (not so unlikely) case that the mmc controller timeout budget is enough for exactly one erase-group, the simplification of allowing one sector has an enormous performance penalty. We optimize this special case by introducing a flag that prohibits erase-group boundary crossing, so that we can allow trimming more than one sector at a time. Signed-off-by: David Jander Signed-off-by: Ulf Hansson --- drivers/mmc/core/core.c | 38 ++++++++++++++++++++++++++++++++++---- include/linux/mmc/card.h | 1 + 2 files changed, 35 insertions(+), 4 deletions(-) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 9ad73f3..083cade 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2168,6 +2168,7 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr, unsigned int arg) { unsigned int rem, to = from + nr; + int err; if (!(card->host->caps & MMC_CAP_ERASE) || !(card->csd.cmdclass & CCC_ERASE)) @@ -2218,6 +2219,23 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr, /* 'from' and 'to' are inclusive */ to -= 1; + /* + * Special case where only one erase-group fits in the timeout budget: + * If the region crosses an erase-group boundary on this particular + * case, we will be trimming more than one erase-group which, does not + * fit in the timeout budget of the controller, so we need to split it + * and call mmc_do_erase() twice if necessary. This special case is + * identified by the card->eg_boundary flag. + */ + if ((arg & MMC_TRIM_ARGS) && (card->eg_boundary) && + (from % card->erase_size)) { + rem = card->erase_size - (from % card->erase_size); + err = mmc_do_erase(card, from, from + rem - 1, arg); + from += rem; + if ((err) || (to <= from)) + return err; + } + return mmc_do_erase(card, from, to, arg); } EXPORT_SYMBOL(mmc_erase); @@ -2313,16 +2331,28 @@ static unsigned int mmc_do_calc_max_discard(struct mmc_card *card, if (!qty) return 0; + /* + * When specifying a sector range to trim, chances are we might cross + * an erase-group boundary even if the amount of sectors is less than + * one erase-group. + * If we can only fit one erase-group in the controller timeout budget, + * we have to care that erase-group boundaries are not crossed by a + * single trim operation. We flag that special case with "eg_boundary". + * In all other cases we can just decrement qty and pretend that we + * always touch (qty + 1) erase-groups as a simple optimization. + */ if (qty == 1) - return 1; + card->eg_boundary = 1; + else + qty--; /* Convert qty to sectors */ if (card->erase_shift) - max_discard = --qty << card->erase_shift; + max_discard = qty << card->erase_shift; else if (mmc_card_sd(card)) - max_discard = qty; + max_discard = qty + 1; else - max_discard = --qty * card->erase_size; + max_discard = qty * card->erase_size; return max_discard; } diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index 4d3776d..8fcbcd1 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -283,6 +283,7 @@ struct mmc_card { unsigned int erase_size; /* erase size in sectors */ unsigned int erase_shift; /* if erase unit is power 2 */ unsigned int pref_erase; /* in sectors */ + unsigned int eg_boundary; /* don't cross erase-group boundaries */ u8 erased_byte; /* value of erased bytes */ u32 raw_cid[4]; /* raw card CID */ -- 2.7.4