RE: PATCH v2 2/6] soc/fsl/qe: qe.c: reduce static memory footprint by 1.7K
From: Qiang Zhao <qiang.zhao@nxp.com>
Date: 2019-05-09 02:30:31
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On 2019/5/1 17:29, Rasmus Villemoes [off-list ref] wrote:
-----Original Message----- From: Rasmus Villemoes <redacted> Sent: 2019年5月1日 17:29 To: devicetree@vger.kernel.org; Qiang Zhao <qiang.zhao@nxp.com>; Leo Li [off-list ref] Cc: linuxppc-dev@lists.ozlabs.org; linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Rob Herring [off-list ref]; Scott Wood [off-list ref]; Christophe Leroy [off-list ref]; Mark Rutland [off-list ref]; Rasmus Villemoes [off-list ref] Subject: [PATCH v2 2/6] soc/fsl/qe: qe.c: reduce static memory footprint by 1.7K The current array of struct qe_snum use 256*4 bytes for just keeping track of the free/used state of each index, and the struct layout means there's another 768 bytes of padding. If we just unzip that structure, the array of snum values just use 256 bytes, while the free/inuse state can be tracked in a 32 byte bitmap. So this reduces the .data footprint by 1760 bytes. It also serves as preparation for introducing another DT binding for specifying the snum values. Signed-off-by: Rasmus Villemoes <redacted>
Reviewed-by: Qiang Zhao <qiang.zhao@nxp.com>
quoted hunk
--- drivers/soc/fsl/qe/qe.c | 43 ++++++++++++----------------------------- 1 file changed, 12 insertions(+), 31 deletions(-)diff --git a/drivers/soc/fsl/qe/qe.c b/drivers/soc/fsl/qe/qe.c index855373deb746..303aa29cb27d 100644--- a/drivers/soc/fsl/qe/qe.c +++ b/drivers/soc/fsl/qe/qe.c@@ -14,6 +14,7 @@ * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. */ +#include <linux/bitmap.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/kernel.h>@@ -43,25 +44,14 @@ static DEFINE_SPINLOCK(qe_lock);DEFINE_SPINLOCK(cmxgcr_lock); EXPORT_SYMBOL(cmxgcr_lock); -/* QE snum state */ -enum qe_snum_state { - QE_SNUM_STATE_USED, - QE_SNUM_STATE_FREE -}; - -/* QE snum */ -struct qe_snum { - u8 num; - enum qe_snum_state state; -}; - /* We allocate this here because it is used almost exclusively for * the communication processor devices. */ struct qe_immap __iomem *qe_immr; EXPORT_SYMBOL(qe_immr); -static struct qe_snum snums[QE_NUM_OF_SNUM]; /* Dynamically allocated SNUMs */ +static u8 snums[QE_NUM_OF_SNUM]; /* Dynamically allocated SNUMs */ +static DECLARE_BITMAP(snum_state, QE_NUM_OF_SNUM); static unsigned int qe_num_of_snum; static phys_addr_t qebase = -1;@@ -315,10 +305,8 @@ static void qe_snums_init(void) else snum_init = snum_init_46; - for (i = 0; i < qe_num_of_snum; i++) { - snums[i].num = snum_init[i]; - snums[i].state = QE_SNUM_STATE_FREE; - } + bitmap_zero(snum_state, QE_NUM_OF_SNUM); + memcpy(snums, snum_init, qe_num_of_snum); } int qe_get_snum(void)@@ -328,12 +316,10 @@ int qe_get_snum(void) int i; spin_lock_irqsave(&qe_lock, flags); - for (i = 0; i < qe_num_of_snum; i++) { - if (snums[i].state == QE_SNUM_STATE_FREE) { - snums[i].state = QE_SNUM_STATE_USED; - snum = snums[i].num; - break; - } + i = find_first_zero_bit(snum_state, qe_num_of_snum); + if (i < qe_num_of_snum) { + set_bit(i, snum_state); + snum = snums[i]; } spin_unlock_irqrestore(&qe_lock, flags);@@ -343,14 +329,9 @@ EXPORT_SYMBOL(qe_get_snum); void qe_put_snum(u8 snum) { - int i; - - for (i = 0; i < qe_num_of_snum; i++) { - if (snums[i].num == snum) { - snums[i].state = QE_SNUM_STATE_FREE; - break; - } - } + const u8 *p = memchr(snums, snum, qe_num_of_snum); + if (p) + clear_bit(p - snums, snum_state); } EXPORT_SYMBOL(qe_put_snum); --2.20.1
Best Regards Qiang Zhao